<XBRL>
<?xml version="1.0" encoding="us-ascii" standalone="no"?>
<!--XBRL document created with Bowne Tagger XBRL Enabler by Bowne Software version 10.0.0.120-->
<!--Based on XBRL 2.1-->
<!--Modified on: 2/29/2012 1:46:41 PM-->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DocumentAndEntityInformation" roleURI="http://willis.com/role/DocumentAndEntityInformation" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#StatementsOfOperations" roleURI="http://willis.com/role/StatementsOfOperations" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#BalanceSheets" roleURI="http://willis.com/role/BalanceSheets" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#BalanceSheetsParenthetical" roleURI="http://willis.com/role/BalanceSheetsParenthetical" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#StatementsOfCashFlows" roleURI="http://willis.com/role/StatementsOfCashFlows" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#NatureOfOperations" roleURI="http://willis.com/role/NatureOfOperations" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#BasisOfPresentationAndSignificantAccountingPolicies" roleURI="http://willis.com/role/BasisOfPresentationAndSignificantAccountingPolicies" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EarningsPerShare" roleURI="http://willis.com/role/EarningsPerShare" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#Goodwill" roleURI="http://willis.com/role/Goodwill" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherIntangibleAssets" roleURI="http://willis.com/role/OtherIntangibleAssets" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherAssets" roleURI="http://willis.com/role/OtherAssets" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherLiabilities" roleURI="http://willis.com/role/OtherLiabilities" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlans" roleURI="http://willis.com/role/PensionPlans" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#Debt" roleURI="http://willis.com/role/Debt" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#CommitmentsAndContingencies" roleURI="http://willis.com/role/CommitmentsAndContingencies" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EquityAndNoncontrollingInterest" roleURI="http://willis.com/role/EquityAndNoncontrollingInterest" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SupplementalDisclosuresOfCashFlowInformation" roleURI="http://willis.com/role/SupplementalDisclosuresOfCashFlowInformation" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DerivativeFinancialInstrumentsAndHedgingActivities" roleURI="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivities" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FairValueMeasurement" roleURI="http://willis.com/role/FairValueMeasurement" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SegmentInformation" roleURI="http://willis.com/role/SegmentInformation" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiaries" roleURI="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiaries" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentIssuerGuarantorSubsidiariesAndNonGuarantorSubsidiaries" roleURI="http://willis.com/role/FinancialInformationForParentIssuerGuarantorSubsidiariesAndNonGuarantorSubsidiaries" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#BasisOfPresentationAndSignificantAccountingPoliciesPolicies" roleURI="http://willis.com/role/BasisOfPresentationAndSignificantAccountingPoliciesPolicies" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DerivativeFinancialInstrumentsAndHedgincActivitiesDetails" roleURI="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgincActivitiesDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DerivativeFinancialInstrumentsAndHedgincActivitiesDetails1" roleURI="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgincActivitiesDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DerivativeFinancialInstrumentsAndHedgingActivitiesDetails2" roleURI="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesDetails2" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DerivativeFinancialInstrumentsAndHedgingActivitiesDetails3" roleURI="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesDetails3" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DerivativeFinancialInstrumentsAndHedgingActivitiesDetails4" roleURI="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesDetails4" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DerivativeFinancialInstrumentsAndHedgingActivitiesTables" roleURI="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherAssetsTables" roleURI="http://willis.com/role/OtherAssetsTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherAssetsDetails" roleURI="http://willis.com/role/OtherAssetsDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherLiabilitiesTables" roleURI="http://willis.com/role/OtherLiabilitiesTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherLiabilitiesDetails" roleURI="http://willis.com/role/OtherLiabilitiesDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EarningsPerShareTables" roleURI="http://willis.com/role/EarningsPerShareTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EarningsPerShareDetails" roleURI="http://willis.com/role/EarningsPerShareDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansTables" roleURI="http://willis.com/role/PensionPlansTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails" roleURI="http://willis.com/role/PensionPlansDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#GoodwillTables" roleURI="http://willis.com/role/GoodwillTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#GoodwillDetails" roleURI="http://willis.com/role/GoodwillDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherIntangibleAssetsNetTables" roleURI="http://willis.com/role/OtherIntangibleAssetsNetTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherIntangibleAssetsNetDetails" roleURI="http://willis.com/role/OtherIntangibleAssetsNetDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#OtherIntangibleAssetsNetDetails1" roleURI="http://willis.com/role/OtherIntangibleAssetsNetDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SupplementalDisclosuresOfCashFlowInformationTables" roleURI="http://willis.com/role/SupplementalDisclosuresOfCashFlowInformationTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SupplementalDisclosuresOfCashFlowInformationDetails" roleURI="http://willis.com/role/SupplementalDisclosuresOfCashFlowInformationDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DebtTables" roleURI="http://willis.com/role/DebtTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DebtDetails" roleURI="http://willis.com/role/DebtDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DebtDetails1" roleURI="http://willis.com/role/DebtDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ComponentsOfComprehensiveIncomeTables" roleURI="http://willis.com/role/ComponentsOfComprehensiveIncomeTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ComponentsOfComprehensiveIncomeDetails" roleURI="http://willis.com/role/ComponentsOfComprehensiveIncomeDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EquityAndNoncontrollingInterestTables" roleURI="http://willis.com/role/EquityAndNoncontrollingInterestTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EquityAndNoncontrollingInterestDetails" roleURI="http://willis.com/role/EquityAndNoncontrollingInterestDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ComprehensiveIncomeDetails1" roleURI="http://willis.com/role/ComprehensiveIncomeDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EquityAndNoncontrollingInterestDetails1" roleURI="http://willis.com/role/EquityAndNoncontrollingInterestDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SegmentInformationTables" roleURI="http://willis.com/role/SegmentInformationTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SegmentInformationDetails" roleURI="http://willis.com/role/SegmentInformationDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SegmentInformationDetailsOne" roleURI="http://willis.com/role/SegmentInformationDetailsOne" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SegmentInformationDetailsTwo" roleURI="http://willis.com/role/SegmentInformationDetailsTwo" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesTables" roleURI="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FairValueMeasurementTable" roleURI="http://willis.com/role/FairValueMeasurementTable" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentIssuerGurantorSubsidiariesAndNonGurantorSubsidiaries" roleURI="http://willis.com/role/FinancialInformationForParentIssuerGurantorSubsidiariesAndNonGurantorSubsidiaries" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentIssuerGurantorSubsidiariesAndNonGurantorSubsidiariesDetailsOne" roleURI="http://willis.com/role/FinancialInformationForParentIssuerGurantorSubsidiariesAndNonGurantorSubsidiariesDetailsOne" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentIssuerGurantorSubsidiariesAndNonGurantorSubsidiariesDetails2" roleURI="http://willis.com/role/FinancialInformationForParentIssuerGurantorSubsidiariesAndNonGurantorSubsidiariesDetails2" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FairValueMeasurementDetails" roleURI="http://willis.com/role/FairValueMeasurementDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FairValueMeasurementDetails1" roleURI="http://willis.com/role/FairValueMeasurementDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetails" roleURI="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetails1" roleURI="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetails2" roleURI="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetails2" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#IncomeTaxes" roleURI="http://willis.com/role/IncomeTaxes" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#IncomeTaxesTables" roleURI="http://willis.com/role/IncomeTaxesTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#IncomeTaxesDetails" roleURI="http://willis.com/role/IncomeTaxesDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SegmentInformationDetailsTextual" roleURI="http://willis.com/role/SegmentInformationDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#StatementsOfChangesInEquityAndComprehensiveIncome" roleURI="http://willis.com/role/StatementsOfChangesInEquityAndComprehensiveIncome" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#Employees" roleURI="http://willis.com/role/Employees" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ShareBasedCompensation" roleURI="http://willis.com/role/ShareBasedCompensation" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#AuditorsRemuneration" roleURI="http://willis.com/role/AuditorsRemuneration" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#NetLossGainOnDisposalOfOperations" roleURI="http://willis.com/role/NetLossGainOnDisposalOfOperations" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FiduciaryAssets" roleURI="http://willis.com/role/FiduciaryAssets" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FixedAssetsNet" roleURI="http://willis.com/role/FixedAssetsNet" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#InvestmentsInAssociates" roleURI="http://willis.com/role/InvestmentsInAssociates" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#AllowanceForDoubtfulAccounts" roleURI="http://willis.com/role/AllowanceForDoubtfulAccounts" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ProvisionsForLiabilities" roleURI="http://willis.com/role/ProvisionsForLiabilities" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#AccumulatedOtherComprehensiveLossNetOfTax" roleURI="http://willis.com/role/AccumulatedOtherComprehensiveLossNetOfTax" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SubsidiaryUndertakings" roleURI="http://willis.com/role/SubsidiaryUndertakings" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#QuarterlyFinancialDataUnaudited" roleURI="http://willis.com/role/QuarterlyFinancialDataUnaudited" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#BasisOfPresentationAndSignificantAccountingPoliciesTables" roleURI="http://willis.com/role/BasisOfPresentationAndSignificantAccountingPoliciesTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#BasisOfPresentationAndSignificantAccountingPoliciesDetailsTextual" roleURI="http://willis.com/role/BasisOfPresentationAndSignificantAccountingPoliciesDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EmployeesTables" roleURI="http://willis.com/role/EmployeesTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EmployeesDetails" roleURI="http://willis.com/role/EmployeesDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EmployeesDetailsOne" roleURI="http://willis.com/role/EmployeesDetailsOne" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EmployeesDeltailsTextual" roleURI="http://willis.com/role/EmployeesDeltailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ShareBasedCompensationDetails" roleURI="http://willis.com/role/ShareBasedCompensationDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ShareBasedCompensationDetails1" roleURI="http://willis.com/role/ShareBasedCompensationDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ShareBasedCompensationTables" roleURI="http://willis.com/role/ShareBasedCompensationTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ShareBasedCompensationDetailsTextual" roleURI="http://willis.com/role/ShareBasedCompensationDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#AuditorsRemunerationTables" roleURI="http://willis.com/role/AuditorsRemunerationTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#AuditorsRemunerationDetails" roleURI="http://willis.com/role/AuditorsRemunerationDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#NetLossGainOnDisposalOfOperationsTables" roleURI="http://willis.com/role/NetLossGainOnDisposalOfOperationsTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#NetLossGainOnDisposalOfOperationsDetails" roleURI="http://willis.com/role/NetLossGainOnDisposalOfOperationsDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#NetLossGainOnDisposalOfOperationsDetailsTextual" roleURI="http://willis.com/role/NetLossGainOnDisposalOfOperationsDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#IncomeTaxesDetails1" roleURI="http://willis.com/role/IncomeTaxesDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#IncomeTaxesDetails2" roleURI="http://willis.com/role/IncomeTaxesDetails2" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#IncomeTaxesDetails2Alternate" roleURI="http://willis.com/role/IncomeTaxesDetails2Alternate" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#IncomeTaxesDetails3" roleURI="http://willis.com/role/IncomeTaxesDetails3" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#IncomeTaxesDetails4" roleURI="http://willis.com/role/IncomeTaxesDetails4" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#IncomeTaxesDetailsTextual" roleURI="http://willis.com/role/IncomeTaxesDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FiduciaryAssetsDetails" roleURI="http://willis.com/role/FiduciaryAssetsDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FixedAssetsNetTables" roleURI="http://willis.com/role/FixedAssetsNetTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FixedAssetsNetDetails" roleURI="http://willis.com/role/FixedAssetsNetDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FixedAssetsNetDetailsTextual" roleURI="http://willis.com/role/FixedAssetsNetDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#InvestmentsInAssociatesTables" roleURI="http://willis.com/role/InvestmentsInAssociatesTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#InvestmentsInAssociatesDetails" roleURI="http://willis.com/role/InvestmentsInAssociatesDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#InvestmentsInAssociatesDetails1" roleURI="http://willis.com/role/InvestmentsInAssociatesDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#InvestmentsInAssociatesDetailsTextual" roleURI="http://willis.com/role/InvestmentsInAssociatesDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#AllowanceForDoubtfulAccountsTables" roleURI="http://willis.com/role/AllowanceForDoubtfulAccountsTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#AllowanceForDoubtfulAccountsDetails" roleURI="http://willis.com/role/AllowanceForDoubtfulAccountsDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails1" roleURI="http://willis.com/role/PensionPlansDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails2" roleURI="http://willis.com/role/PensionPlansDetails2" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails3" roleURI="http://willis.com/role/PensionPlansDetails3" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails4" roleURI="http://willis.com/role/PensionPlansDetails4" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDtails5" roleURI="http://willis.com/role/PensionPlansDtails5" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails6" roleURI="http://willis.com/role/PensionPlansDetails6" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails7" roleURI="http://willis.com/role/PensionPlansDetails7" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetailsEight" roleURI="http://willis.com/role/PensionPlansDetailsEight" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetailsNine" roleURI="http://willis.com/role/PensionPlansDetailsNine" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetailsTen" roleURI="http://willis.com/role/PensionPlansDetailsTen" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetailsTextual" roleURI="http://willis.com/role/PensionPlansDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#AccumulatedOtherComprehensiveLossNetOfTaxDetailsTextual" roleURI="http://willis.com/role/AccumulatedOtherComprehensiveLossNetOfTaxDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EarningsPerShareDetailsTextual" roleURI="http://willis.com/role/EarningsPerShareDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails11" roleURI="http://willis.com/role/PensionPlansDetails11" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails12" roleURI="http://willis.com/role/PensionPlansDetails12" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails13" roleURI="http://willis.com/role/PensionPlansDetails13" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#PensionPlansDetails14" roleURI="http://willis.com/role/PensionPlansDetails14" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ProvisionsForLiabilitiesTables" roleURI="http://willis.com/role/ProvisionsForLiabilitiesTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#ProvisionsForLiabilitiesDetails" roleURI="http://willis.com/role/ProvisionsForLiabilitiesDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#CommitmentsAndContingenciesTables" roleURI="http://willis.com/role/CommitmentsAndContingenciesTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#CommitmentsAndContingenciesDetails1" roleURI="http://willis.com/role/CommitmentsAndContingenciesDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#CommitmentsAndContingenciesDetails2" roleURI="http://willis.com/role/CommitmentsAndContingenciesDetails2" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#CommitmentsAndContingenciesDetailsTextual" roleURI="http://willis.com/role/CommitmentsAndContingenciesDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#CommitmentsAndContingenciesAlternativeDetails1" roleURI="http://willis.com/role/CommitmentsAndContingenciesAlternativeDetails1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SegmentInformationDetails3" roleURI="http://willis.com/role/SegmentInformationDetails3" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SegmentInformationDetails4" roleURI="http://willis.com/role/SegmentInformationDetails4" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#QuarterlyFinancialDataUnauditedDetails" roleURI="http://willis.com/role/QuarterlyFinancialDataUnauditedDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EmployeesDetails2" roleURI="http://willis.com/role/EmployeesDetails2" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#EmployeesDetails3" roleURI="http://willis.com/role/EmployeesDetails3" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SubsidiaryUndertakingsTables" roleURI="http://willis.com/role/SubsidiaryUndertakingsTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#SubsidiaryUndertakingsDetails" roleURI="http://willis.com/role/SubsidiaryUndertakingsDetails" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DebtDetailsTextual" roleURI="http://willis.com/role/DebtDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DiscontinuedOperations" roleURI="http://willis.com/role/DiscontinuedOperations" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DiscontinuedOperationsDetail" roleURI="http://willis.com/role/DiscontinuedOperationsDetail" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DiscontinuedOperationsDetail1" roleURI="http://willis.com/role/DiscontinuedOperationsDetail1" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DiscontinuedOperationsDetailTextual" roleURI="http://willis.com/role/DiscontinuedOperationsDetailTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DerivativeFinancialInstrumentsAndHedgingActivitiesDetails5" roleURI="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesDetails5" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentIssuerGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetailsTextual" roleURI="http://willis.com/role/FinancialInformationForParentIssuerGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetailsTextual" roleURI="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetailsTextual" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#DiscontinuedOperationTables" roleURI="http://willis.com/role/DiscontinuedOperationTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#QuarterlyFinancialDataUnauditedTables" roleURI="http://willis.com/role/QuarterlyFinancialDataUnauditedTables" />
  <roleRef xlink:type="simple" xlink:href="wsh-20111231.xsd#FinancialInformationForParentIssuerGuarantorSubsidiariesAndNonGuarantorSubsidiariesTables" roleURI="http://willis.com/role/FinancialInformationForParentIssuerGuarantorSubsidiariesAndNonGuarantorSubsidiariesTables" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DocumentAndEntityInformation" xlink:title="00 - Document - Document and Entity Information" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/StatementsOfOperations" xlink:title="0110 - Statement - Consolidated Statements of Operations">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_ProfitLoss" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:label="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" order="40" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity" xlink:label="loc_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_ProfitLoss" xlink:to="loc_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_ProfitLoss" xlink:to="loc_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_IncomeLossFromContinuingOperationsBeforeInterestInEarningsOfAssociates" xlink:label="wsh_IncomeLossFromContinuingOperationsBeforeInterestInEarningsOfAssociates" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xlink:to="wsh_IncomeLossFromContinuingOperationsBeforeInterestInEarningsOfAssociates" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_IncomeLossFromContinuingOperationsBeforeInterestInEarningsOfAssociates" xlink:to="us-gaap_IncomeTaxExpenseBenefit" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_IncomeLossFromContinuingOperationsBeforeInterestInEarningsOfAssociates" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="us-gaap_OperatingIncomeLoss" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Revenues" xlink:label="us-gaap_Revenues" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_Revenues" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_InvestmentIncome" xlink:label="wsh_InvestmentIncome" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="wsh_InvestmentIncome" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InsuranceCommissionsAndFees" xlink:label="us-gaap_InsuranceCommissionsAndFees" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="us-gaap_InsuranceCommissionsAndFees" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherIncome" xlink:label="us-gaap_OtherIncome" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="us-gaap_OtherIncome" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="us-gaap_OperatingExpenses" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_OperatingExpenses" order="40" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NetGainLossOnDisposalOfOperations" xlink:label="wsh_NetGainLossOnDisposalOfOperations" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="wsh_NetGainLossOnDisposalOfOperations" order="40" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Depreciation" xlink:label="us-gaap_Depreciation" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_Depreciation" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LaborAndRelatedExpense" xlink:label="us-gaap_LaborAndRelatedExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_LaborAndRelatedExpense" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherCostAndExpenseOperating" xlink:label="us-gaap_OtherCostAndExpenseOperating" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_OtherCostAndExpenseOperating" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InterestExpense" xlink:label="us-gaap_InterestExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="us-gaap_InterestExpense" order="60" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotesAndWriteOffOfUnamortizedDebtIssuanceCosts" xlink:label="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotesAndWriteOffOfUnamortizedDebtIssuanceCosts_2" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotesAndWriteOffOfUnamortizedDebtIssuanceCosts_2" order="50" use="optional" weight="-1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/BalanceSheets" xlink:title="0120 - Statement - Consolidated Balance Sheets">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_AssetsCurrent" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="us-gaap_AccountsReceivableNetCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_AccountsReceivableNetCurrent" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_FiduciaryAssets" xlink:label="wsh_FiduciaryAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="wsh_FiduciaryAssets" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsNetCurrent" xlink:label="us-gaap_DeferredTaxAssetsNetCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_DeferredTaxAssetsNetCurrent" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="us-gaap_OtherAssetsCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_OtherAssetsCurrent" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AssetsNoncurrent" xlink:label="us-gaap_AssetsNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_AssetsNoncurrent" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNoncurrent" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNoncurrent" xlink:to="us-gaap_Goodwill" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNoncurrent" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_EquityMethodInvestments" xlink:label="us-gaap_EquityMethodInvestments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNoncurrent" xlink:to="us-gaap_EquityMethodInvestments" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsNetNoncurrent" xlink:label="us-gaap_DeferredTaxAssetsNetNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNoncurrent" xlink:to="us-gaap_DeferredTaxAssetsNetNoncurrent" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" xlink:label="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNoncurrent" xlink:to="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" order="120" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="us-gaap_OtherAssetsNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNoncurrent" xlink:to="us-gaap_OtherAssetsNoncurrent" order="140" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_Liabilities" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="us-gaap_LiabilitiesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_LiabilitiesCurrent" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DeferredRevenueAndAccruedExpenses" xlink:label="wsh_DeferredRevenueAndAccruedExpenses" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="wsh_DeferredRevenueAndAccruedExpenses" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccruedIncomeTaxesCurrent" xlink:label="us-gaap_AccruedIncomeTaxesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_AccruedIncomeTaxesCurrent" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DebtCurrent" xlink:label="us-gaap_DebtCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_DebtCurrent" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesCurrent" xlink:label="us-gaap_DeferredTaxLiabilitiesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_DeferredTaxLiabilitiesCurrent" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="us-gaap_OtherLiabilitiesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_OtherLiabilitiesCurrent" order="120" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesNoncurrent" xlink:label="us-gaap_LiabilitiesNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_LiabilitiesNoncurrent" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="us-gaap_LongTermDebtNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesNoncurrent" xlink:to="us-gaap_LongTermDebtNoncurrent" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:label="us-gaap_DeferredTaxLiabilitiesNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesNoncurrent" xlink:to="us-gaap_DeferredTaxLiabilitiesNoncurrent" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" xlink:label="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesNoncurrent" xlink:to="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="us-gaap_OtherLiabilitiesNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesNoncurrent" xlink:to="us-gaap_OtherLiabilitiesNoncurrent" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="us-gaap_StockholdersEquity" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_CommonStockValue" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_TreasuryStockValue" xlink:label="us-gaap_TreasuryStockValue" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_TreasuryStockValue" order="120" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_MinorityInterest" xlink:label="us-gaap_MinorityInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="us-gaap_MinorityInterest" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LitigationReserveNoncurrent" xlink:label="loc_LitigationReserveNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesNoncurrent" xlink:to="loc_LitigationReserveNoncurrent" order="40" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_FiduciaryLiabilities" xlink:label="wsh_FiduciaryLiabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="wsh_FiduciaryLiabilities" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_PreferredStockValue" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="loc_PreferredStockValue" order="40" use="optional" weight="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/BalanceSheetsParenthetical" xlink:title="0121 - Statement - Consolidated Balance Sheets (Parenthetical)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/StatementsOfCashFlows" xlink:title="0130 - Statement - Condensed Consolidated Statements of Cash Flows">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_IncreaseDecreaseInCashAndCashEquivalentsFromOperatingAndInvestingActivities" xlink:label="wsh_IncreaseDecreaseInCashAndCashEquivalentsFromOperatingAndInvestingActivities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="wsh_IncreaseDecreaseInCashAndCashEquivalentsFromOperatingAndInvestingActivities" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_IncreaseDecreaseInCashAndCashEquivalentsFromOperatingAndInvestingActivities" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_IncreaseDecreaseInCashAndCashEquivalentsFromOperatingAndInvestingActivities" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquireEquityMethodInvestments" xlink:label="us-gaap_PaymentsToAcquireEquityMethodInvestments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_PaymentsToAcquireEquityMethodInvestments" order="100" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" order="140" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" order="160" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromSaleOfProductiveAssets" xlink:label="us-gaap_ProceedsFromSaleOfProductiveAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_ProceedsFromSaleOfProductiveAssets" order="180" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquireOtherInvestments" xlink:label="loc_PaymentsToAcquireOtherInvestments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="loc_PaymentsToAcquireOtherInvestments" order="120" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RepaymentsOfOtherDebt" xlink:label="us-gaap_RepaymentsOfOtherDebt" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_RepaymentsOfOtherDebt" order="40" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromUnsecuredLinesOfCredit" xlink:label="us-gaap_ProceedsFromUnsecuredLinesOfCredit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromUnsecuredLinesOfCredit" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsOfDividendsMinorityInterest" xlink:label="us-gaap_PaymentsOfDividendsMinorityInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsOfDividendsMinorityInterest" order="80" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries" xlink:label="us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries" order="100" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock" xlink:label="us-gaap_PaymentsOfDividendsCommonStock" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsOfDividendsCommonStock" order="120" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" order="140" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="160" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsOfDebtIssuanceCosts" xlink:label="loc_PaymentsOfDebtIssuanceCosts" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="loc_PaymentsOfDebtIssuanceCosts" order="200" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromIssuanceOfMediumTermNotes" xlink:label="us-gaap_ProceedsFromIssuanceOfMediumTermNotes" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromIssuanceOfMediumTermNotes" order="220" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:label="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity" xlink:label="loc_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="loc_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity" order="100" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Depreciation" xlink:label="us-gaap_Depreciation" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_Depreciation" order="120" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInRestrictedCashForOperatingActivities" xlink:label="loc_IncreaseDecreaseInRestrictedCashForOperatingActivities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="loc_IncreaseDecreaseInRestrictedCashForOperatingActivities" order="140" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ChangeInFiduciaryLiabilities" xlink:label="wsh_ChangeInFiduciaryLiabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="wsh_ChangeInFiduciaryLiabilities" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_IncreaseDecreaseInAccountsReceivable" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="loc_IncreaseDecreaseInAccountsReceivable" order="160" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInOtherOperatingAssets" order="180" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossUnrealized" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_ForeignCurrencyTransactionGainLossUnrealized" order="200" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_EffectOfExchangeRateChangesOnNetIncome" xlink:label="wsh_EffectOfExchangeRateChangesOnNetIncome" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="wsh_EffectOfExchangeRateChangesOnNetIncome" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" order="220" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions" order="240" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_ShareBasedCompensation" order="260" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities" xlink:label="us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities" order="280" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredIncomeTaxes" xlink:label="us-gaap_IncreaseDecreaseInDeferredIncomeTaxes" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInDeferredIncomeTaxes" order="300" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense" order="320" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="loc_ProvisionForDoubtfulAccounts" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="loc_ProvisionForDoubtfulAccounts" order="340" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_GainLossOnSaleOfOtherAssets" xlink:label="us-gaap_GainLossOnSaleOfOtherAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_GainLossOnSaleOfOtherAssets" order="360" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_ProfitLoss" order="380" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" xlink:label="loc_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="loc_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:label="loc_ProceedsFromSaleOfEquityMethodInvestments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="loc_ProceedsFromSaleOfEquityMethodInvestments" order="80" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ProceedsFromSaleOfContinuingOperationsNetOfCashDisposed" xlink:label="wsh_ProceedsFromSaleOfContinuingOperationsNetOfCashDisposed" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="wsh_ProceedsFromSaleOfContinuingOperationsNetOfCashDisposed" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" xlink:label="loc_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="loc_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" order="40" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" xlink:label="loc_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="loc_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" order="20" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_PaymentsForRepurchaseOfCommonStock" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="loc_PaymentsForRepurchaseOfCommonStock" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotes" xlink:label="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotes" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotes" order="210" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotesAndWriteOffOfUnamortizedDebtIssuanceCosts" xlink:label="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotesAndWriteOffOfUnamortizedDebtIssuanceCosts_2" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotesAndWriteOffOfUnamortizedDebtIssuanceCosts_2" order="270" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_IncreaseDecreaseInProvisions" xlink:label="wsh_IncreaseDecreaseInProvisions" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="wsh_IncreaseDecreaseInProvisions" order="30" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/NatureOfOperations" xlink:title="0201 - Disclosure - Nature of Operations" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/BasisOfPresentationAndSignificantAccountingPolicies" xlink:title="0202 - Disclosure - Basis of Presentation and Significant Accounting Policies" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EarningsPerShare" xlink:title="0209 - Disclosure - Earnings Per Share" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/Goodwill" xlink:title="0212 - Disclosure - Goodwill" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherIntangibleAssets" xlink:title="0213 - Disclosure - Other Intangible Assets, Net" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherAssets" xlink:title="0215 - Disclosure - Other Assets" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherLiabilities" xlink:title="0216 - Disclosure - Other Liabilities" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlans" xlink:title="0218 - Disclosure - Pension Plans" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/Debt" xlink:title="0219 - Disclosure - Debt" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/CommitmentsAndContingencies" xlink:title="0221 - Disclosure - Commitments and Contingencies" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EquityAndNoncontrollingInterest" xlink:title="0223 - Disclosure - Equity and Noncontrolling Interests" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SupplementalDisclosuresOfCashFlowInformation" xlink:title="0224 - Disclosure - Supplemental Disclosures of Cash Flow Information" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivities" xlink:title="0225 - Disclosure - Derivative Financial Instruments and Hedging Activities" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FairValueMeasurement" xlink:title="0226 - Disclosure - Fair Value Measurements" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SegmentInformation" xlink:title="0227 - Disclosure - Segment Information" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiaries" xlink:title="0229 - Disclosure - Financial Information for Parent Guarantor, Other Guarantor Subsidiaries and Non-Guarantor Subsidiaries" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentIssuerGuarantorSubsidiariesAndNonGuarantorSubsidiaries" xlink:title="0230 - Disclosure - Financial Information for Parent Issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/BasisOfPresentationAndSignificantAccountingPoliciesPolicies" xlink:title="0402 - Disclosure - Basis of Presentation and Significant Accounting Policies (Policies)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgincActivitiesDetails" xlink:title="0625 - Disclosure - Derivative Financial Instruments and Hedging Activities (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgincActivitiesDetails1" xlink:title="062502 - Disclosure - Derivative Financial Instruments and Hedging Activities (Details 2)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesDetails2" xlink:title="062503 - Disclosure - Derivative Financial Instruments and Hedging Activities (Details 3)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesDetails3" xlink:title="062504 - Disclosure - Derivative Financial Instruments and Hedging Activities (Details 4)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_GainLossOnFairValueHedgeIneffectivenessNet" xlink:label="loc_GainLossOnFairValueHedgeIneffectivenessNet" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge" xlink:label="loc_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_GainLossOnFairValueHedgeIneffectivenessNet" xlink:to="loc_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments" xlink:label="loc_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_GainLossOnFairValueHedgeIneffectivenessNet" xlink:to="loc_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments" order="40" use="optional" weight="-1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesDetails4" xlink:title="062505 - Disclosure - Derivative Financial Instruments and Hedging Activities (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesTables" xlink:title="0525 - Disclosure - Derivative Financial Instruments and Hedging Activities (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherAssetsTables" xlink:title="0515 - Disclosure - Other Assets (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherAssetsDetails" xlink:title="0615 - Disclosure - Other Assets (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherAssets" xlink:label="us-gaap_OtherAssets" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="us-gaap_OtherAssetsNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssets" xlink:to="us-gaap_OtherAssetsNoncurrent" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OtherReceivableNonCurrent" xlink:label="wsh_OtherReceivableNonCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsNoncurrent" xlink:to="wsh_OtherReceivableNonCurrent" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_UnamortizedDebtIssuanceExpense" xlink:label="loc_UnamortizedDebtIssuanceExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsNoncurrent" xlink:to="loc_UnamortizedDebtIssuanceExpense" order="10" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DerivativeAssetsNoncurrent" xlink:label="loc_DerivativeAssetsNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsNoncurrent" xlink:to="loc_DerivativeAssetsNoncurrent" order="5" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_UnamortizedCashRetentionAwardsNonCurrent" xlink:label="wsh_UnamortizedCashRetentionAwardsNonCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsNoncurrent" xlink:to="wsh_UnamortizedCashRetentionAwardsNonCurrent" order="2.5" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredCompensationPlanAssets" xlink:label="loc_DeferredCompensationPlanAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsNoncurrent" xlink:to="loc_DeferredCompensationPlanAssets" order="1.25" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="us-gaap_OtherAssetsCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssets" xlink:to="us-gaap_OtherAssetsCurrent" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OtherReceivablesCurrent" xlink:label="wsh_OtherReceivablesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsCurrent" xlink:to="wsh_OtherReceivablesCurrent" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_UnamortizedDebtIssuanceExpenseCurrent" xlink:label="wsh_UnamortizedDebtIssuanceExpenseCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsCurrent" xlink:to="wsh_UnamortizedDebtIssuanceExpenseCurrent" order="10" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DerivativeAssetsCurrent" xlink:label="loc_DerivativeAssetsCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsCurrent" xlink:to="loc_DerivativeAssetsCurrent" order="5" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxesReceivable" xlink:label="us-gaap_IncomeTaxesReceivable_2" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsCurrent" xlink:to="us-gaap_IncomeTaxesReceivable_2" order="2.5" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_PrepaidExpenseOtherAssetsAndUnbilledReceivablesCurrent" xlink:label="wsh_PrepaidExpenseOtherAssetsAndUnbilledReceivablesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsCurrent" xlink:to="wsh_PrepaidExpenseOtherAssetsAndUnbilledReceivablesCurrent" order="1.25" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_UnamortizedCashRetentionAwardsCurrent" xlink:label="wsh_UnamortizedCashRetentionAwardsCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherAssetsCurrent" xlink:to="wsh_UnamortizedCashRetentionAwardsCurrent" order="0.625" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherLiabilitiesTables" xlink:title="0516 - Disclosure - Other Liabilities (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherLiabilitiesDetails" xlink:title="0616 - Disclosure - Other Liabilities (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="us-gaap_OtherLiabilitiesNoncurrent" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CapitalLeaseObligationsNoncurrent" xlink:label="loc_CapitalLeaseObligationsNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="loc_CapitalLeaseObligationsNoncurrent" order="100" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:label="loc_DeferredCompensationLiabilityClassifiedNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="loc_DeferredCompensationLiabilityClassifiedNoncurrent" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DerivativeLiabilitiesNoncurrent" xlink:label="loc_DerivativeLiabilitiesNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="loc_DerivativeLiabilitiesNoncurrent" order="60" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccruedRentNoncurrent" xlink:label="loc_AccruedRentNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="loc_AccruedRentNoncurrent" order="20" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherLiabilities" xlink:label="loc_OtherLiabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_OtherLiabilities" xlink:to="us-gaap_OtherLiabilitiesNoncurrent" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="us-gaap_OtherLiabilitiesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_OtherLiabilities" xlink:to="us-gaap_OtherLiabilitiesCurrent" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherSundryLiabilitiesCurrent" xlink:label="loc_OtherSundryLiabilitiesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesCurrent" xlink:to="loc_OtherSundryLiabilitiesCurrent" order="20" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="loc_DerivativeLiabilitiesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesCurrent" xlink:to="loc_DerivativeLiabilitiesCurrent" order="40" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InterestPayableCurrent" xlink:label="loc_InterestPayableCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesCurrent" xlink:to="loc_InterestPayableCurrent" order="60" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DividendsPayableCurrent" xlink:label="loc_DividendsPayableCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesCurrent" xlink:to="loc_DividendsPayableCurrent" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_AccountsPayableCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesCurrent" xlink:to="loc_AccountsPayableCurrent" order="120" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_AccrualForTaxesOtherThanIncomeTaxCurrent" xlink:label="wsh_AccrualForTaxesOtherThanIncomeTaxCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesCurrent" xlink:to="wsh_AccrualForTaxesOtherThanIncomeTaxCurrent" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OtherPayables" xlink:label="wsh_OtherPayables" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="wsh_OtherPayables" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_AccrualForTaxesOtherThanIncomeTaxesNoncurrent" xlink:label="wsh_AccrualForTaxesOtherThanIncomeTaxesNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="wsh_AccrualForTaxesOtherThanIncomeTaxesNoncurrent" order="70" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EarningsPerShareTables" xlink:title="0509 - Disclosure - Earnings Per Share (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EarningsPerShareDetails" xlink:title="0609 - Disclosure - Earnings Per Share (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_EarningsPerShareDiluted" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" xlink:label="loc_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_EarningsPerShareDiluted" xlink:to="loc_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" xlink:label="loc_IncomeLossFromContinuingOperationsPerDilutedShare" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_EarningsPerShareDiluted" xlink:to="loc_IncomeLossFromContinuingOperationsPerDilutedShare" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_WeightedAverageNumberOfDilutedSharesOutstanding" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="loc_WeightedAverageNumberDilutedSharesOutstandingAdjustment" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="loc_WeightedAverageNumberDilutedSharesOutstandingAdjustment" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_WeightedAverageNumberOfSharesOutstandingBasic" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="loc_WeightedAverageNumberOfSharesOutstandingBasic" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_EarningsPerShareBasic" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" xlink:label="loc_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_EarningsPerShareBasic" xlink:to="loc_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" xlink:label="loc_IncomeLossFromContinuingOperationsPerBasicShare" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_EarningsPerShareBasic" xlink:to="loc_IncomeLossFromContinuingOperationsPerBasicShare" order="20" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansTables" xlink:title="0518 - Disclosure - Pension Plans (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails" xlink:title="0618 - Disclosure - Pension Plans (Details)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/GoodwillTables" xlink:title="0512 - Disclosure - Goodwill (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/GoodwillDetails" xlink:title="0612 - Disclosure - Goodwill (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherIntangibleAssetsNetTables" xlink:title="0513 - Disclosure - Other Intangible Assets, Net (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherIntangibleAssetsNetDetails" xlink:title="0613 - Disclosure - Other Intangible Assets, Net (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_FiniteLivedIntangibleAssetsNet" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_FiniteLivedIntangibleAssetsAccumulatedAmortization" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_FiniteLivedIntangibleAssetsNet" xlink:to="loc_FiniteLivedIntangibleAssetsAccumulatedAmortization" order="40" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_FiniteLivedIntangibleAssetsGross" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_FiniteLivedIntangibleAssetsNet" xlink:to="loc_FiniteLivedIntangibleAssetsGross" order="20" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/OtherIntangibleAssetsNetDetails1" xlink:title="06131 - Disclosure - Other Intangible Assets, Net (Details 1)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpense" xlink:label="loc_FiniteLivedIntangibleAssetsFutureAmortizationExpense" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FutureAmortizationExpenseYearFour" xlink:label="loc_FutureAmortizationExpenseYearFour" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_FiniteLivedIntangibleAssetsFutureAmortizationExpense" xlink:to="loc_FutureAmortizationExpenseYearFour" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FutureAmortizationExpenseYearThree" xlink:label="loc_FutureAmortizationExpenseYearThree" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_FiniteLivedIntangibleAssetsFutureAmortizationExpense" xlink:to="loc_FutureAmortizationExpenseYearThree" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FutureAmortizationExpenseYearTwo" xlink:label="loc_FutureAmortizationExpenseYearTwo" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_FiniteLivedIntangibleAssetsFutureAmortizationExpense" xlink:to="loc_FutureAmortizationExpenseYearTwo" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FutureAmortizationExpenseYearOne" xlink:label="loc_FutureAmortizationExpenseYearOne" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_FiniteLivedIntangibleAssetsFutureAmortizationExpense" xlink:to="loc_FutureAmortizationExpenseYearOne" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FutureAmortizationExpenseYearFive" xlink:label="loc_FutureAmortizationExpenseYearFive" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_FiniteLivedIntangibleAssetsFutureAmortizationExpense" xlink:to="loc_FutureAmortizationExpenseYearFive" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FutureAmortizationExpenseAfterYearFive" xlink:label="loc_FutureAmortizationExpenseAfterYearFive" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_FiniteLivedIntangibleAssetsFutureAmortizationExpense" xlink:to="loc_FutureAmortizationExpenseAfterYearFive" order="120" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SupplementalDisclosuresOfCashFlowInformationTables" xlink:title="0524 - Disclosure - Supplemental Disclosures of Cash Flow Information (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SupplementalDisclosuresOfCashFlowInformationDetails" xlink:title="0624 - Disclosure - Supplemental Disclosures of Cash Flow Information (Details)">
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NetAssetsLiabilitiesAcquiredNetOfCashAcquired" xlink:label="wsh_NetAssetsLiabilitiesAcquiredNetOfCashAcquired" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesAssumed1" xlink:label="loc_LiabilitiesAssumed1" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NetAssetsLiabilitiesAcquiredNetOfCashAcquired" xlink:to="loc_LiabilitiesAssumed1" order="40" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FairValueOfAssetsAcquired" xlink:label="loc_FairValueOfAssetsAcquired" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NetAssetsLiabilitiesAcquiredNetOfCashAcquired" xlink:to="loc_FairValueOfAssetsAcquired" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CashAcquiredFromAcquisition" xlink:label="loc_CashAcquiredFromAcquisition" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NetAssetsLiabilitiesAcquiredNetOfCashAcquired" xlink:to="loc_CashAcquiredFromAcquisition" order="60" use="optional" weight="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DebtTables" xlink:title="0519 - Disclosure - Debt (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DebtDetails" xlink:title="0619 - Disclosure - Debt (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DebtCurrent" xlink:label="us-gaap_DebtCurrent" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherNotesPayableCurrent" xlink:label="loc_OtherNotesPayableCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DebtCurrent" xlink:to="loc_OtherNotesPayableCurrent" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LoansPayableToBankCurrent" xlink:label="loc_LoansPayableToBankCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DebtCurrent" xlink:to="loc_LoansPayableToBankCurrent" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="us-gaap_LongTermDebtNoncurrent" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_SeniorLongTermNotes" xlink:label="loc_SeniorLongTermNotes" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LongTermDebtNoncurrent" xlink:to="loc_SeniorLongTermNotes" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherLoansPayableLongTerm" xlink:label="loc_OtherLoansPayableLongTerm" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LongTermDebtNoncurrent" xlink:to="loc_OtherLoansPayableLongTerm" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LineOfCreditFacilityAmountOutstanding" xlink:label="loc_LineOfCreditFacilityAmountOutstanding" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LongTermDebtNoncurrent" xlink:to="loc_LineOfCreditFacilityAmountOutstanding" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LongTermLoansFromBank" xlink:label="loc_LongTermLoansFromBank" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LongTermDebtNoncurrent" xlink:to="loc_LongTermLoansFromBank" order="20" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DebtDetails1" xlink:title="061901 - Disclosure - Debt (Details 1)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ComponentsOfComprehensiveIncomeTables" xlink:title="0522 - Disclosure - Accumulated Other Comprehensive Loss, Net of Tax (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ComponentsOfComprehensiveIncomeDetails" xlink:title="0622 - Disclosure - Accumulated Other Comprehensive Loss, Net of Tax (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_ComprehensiveIncomeNetOfTax" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" xlink:label="loc_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ComprehensiveIncomeNetOfTax" xlink:to="loc_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" order="20" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ComprehensiveIncomeNetOfTax" xlink:to="loc_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" order="40" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:label="loc_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:to="loc_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" xlink:label="loc_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:to="loc_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPeriodIncreaseDecrease" xlink:label="loc_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPeriodIncreaseDecrease" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:to="loc_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPeriodIncreaseDecrease" order="60" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPeriodIncreaseDecrease" xlink:label="loc_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPeriodIncreaseDecrease" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:to="loc_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPeriodIncreaseDecrease" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:to="us-gaap_ProfitLoss" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:to="loc_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" order="20" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EquityAndNoncontrollingInterestTables" xlink:title="0523 - Disclosure - Equity and Noncontrolling Interest (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EquityAndNoncontrollingInterestDetails" xlink:title="0623 - Disclosure - Equity and Noncontrolling Interests (Details)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ComprehensiveIncomeDetails1" xlink:title="06221 - Disclosure - Accumulated Other Comprehensive Loss, Net of Tax (Details 1)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_AccumulatedOtherComprehensiveIncomeLossNetOfTax" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax" xlink:label="loc_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="loc_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax" xlink:label="loc_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="loc_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax" order="60" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax" xlink:label="loc_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="loc_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax" xlink:label="loc_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="loc_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax" order="20" use="optional" weight="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EquityAndNoncontrollingInterestDetails1" xlink:title="06231 - Disclosure - Equity and Noncontrolling Interests (Details 1)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangeDueToNetIncomeAttributableToParentAndEffectsOfChangesNet" xlink:label="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangeDueToNetIncomeAttributableToParentAndEffectsOfChangesNet" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesNet" xlink:label="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesNet" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangeDueToNetIncomeAttributableToParentAndEffectsOfChangesNet" xlink:to="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesNet" order="0.625" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesSaleOfInterestByParent" xlink:label="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesSaleOfInterestByParent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesNet" xlink:to="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesSaleOfInterestByParent" order="10" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesPurchaseOfInterestByParent" xlink:label="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesPurchaseOfInterestByParent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesNet" xlink:to="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesPurchaseOfInterestByParent" order="5" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangeDueToNetIncomeAttributableToParentAndEffectsOfChangesNet" xlink:to="us-gaap_NetIncomeLoss" order="0.9375" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SegmentInformationTables" xlink:title="0527 - Disclosure - Segment Information (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SegmentInformationDetails" xlink:title="0627 - Disclosure - Segment Information (Details)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SegmentInformationDetailsOne" xlink:title="062701 - Disclosure - Segment Information (Details 1)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_EffectOfExchangeRateChangesOnNetIncome" xlink:label="wsh_EffectOfExchangeRateChangesOnNetIncome" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="wsh_EffectOfExchangeRateChangesOnNetIncome" order="120" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OperationalReview" xlink:label="wsh_OperationalReview" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="wsh_OperationalReview" order="160" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" xlink:label="loc_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="loc_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" order="180" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_GainLossOnComponentsExcludedFromAssessmentOfForeignCurrencyCashFlowHedgeEffectiveness" xlink:label="loc_GainLossOnComponentsExcludedFromAssessmentOfForeignCurrencyCashFlowHedgeEffectiveness" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="loc_GainLossOnComponentsExcludedFromAssessmentOfForeignCurrencyCashFlowHedgeEffectiveness" order="200" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense" order="220" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation" xlink:label="loc_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="loc_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_RegulatorySettlement" xlink:label="wsh_RegulatorySettlement" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="wsh_RegulatorySettlement" order="140" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_RedomicileOfParentCompanyCosts" xlink:label="wsh_RedomicileOfParentCompanyCosts_2" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="wsh_RedomicileOfParentCompanyCosts_2" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OtherIncomeAndOtherExpense" xlink:label="wsh_OtherIncomeAndOtherExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="wsh_OtherIncomeAndOtherExpense" order="10" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_WriteOffOfUncollectibleTradeReceivableBalance" xlink:label="wsh_WriteOffOfUncollectibleTradeReceivableBalance" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="wsh_WriteOffOfUncollectibleTradeReceivableBalance" order="50" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_BusinessCombinationIntegrationRelatedCosts" xlink:label="loc_BusinessCombinationIntegrationRelatedCosts" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="loc_BusinessCombinationIntegrationRelatedCosts" order="100" use="optional" weight="-1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SegmentInformationDetailsTwo" xlink:title="062702 - Disclosure - Segment Information (Details 2)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InterestExpense" xlink:label="us-gaap_InterestExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="us-gaap_InterestExpense" order="60" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="us-gaap_OperatingIncomeLoss" order="20" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesTables" xlink:title="0529 - Disclosure - Financial Information for Parent Guarantor, Other Guarantor Subsidiaries and Non Guarantor Subsidiaries (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FairValueMeasurementTable" xlink:title="0526 - Disclosure - Fair Value Measurement (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentIssuerGurantorSubsidiariesAndNonGurantorSubsidiaries" xlink:title="0630 - Disclosure - Financial Information for Parent Issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentIssuerGurantorSubsidiariesAndNonGurantorSubsidiariesDetailsOne" xlink:title="06301 - Disclosure - Financial Information for Parent Issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details 1)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentIssuerGurantorSubsidiariesAndNonGurantorSubsidiariesDetails2" xlink:title="06302 - Disclosure - Financial Information for Parent Issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details 2)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FairValueMeasurementDetails" xlink:title="0626 - Disclosure - Fair Value Measurement (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DerivativeAssets" xlink:label="loc_DerivativeAssets" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_AssetsFairValueDisclosure" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_LiabilitiesFairValueDisclosure" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:label="loc_CashAndCashEquivalentsFairValueDisclosure" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AssetsFairValueDisclosure" xlink:to="loc_CashAndCashEquivalentsFairValueDisclosure" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DerivativeFinancialInstrumentsLiabilitiesFairValueDisclosure" xlink:label="loc_DerivativeFinancialInstrumentsLiabilitiesFairValueDisclosure" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_LiabilitiesFairValueDisclosure" xlink:to="loc_DerivativeFinancialInstrumentsLiabilitiesFairValueDisclosure" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DebtInstrumentFairValue" xlink:label="loc_DebtInstrumentFairValue" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_LiabilitiesFairValueDisclosure" xlink:to="loc_DebtInstrumentFairValue" order="40" use="optional" weight="1" priority="1" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AssetsFairValueDisclosure" xlink:to="loc_DerivativeAssets" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_FiduciaryFundsRestrictedFairValueDisclosure" xlink:label="wsh_FiduciaryFundsRestrictedFairValueDisclosure" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AssetsFairValueDisclosure" xlink:to="wsh_FiduciaryFundsRestrictedFairValueDisclosure" order="40" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FairValueMeasurementDetails1" xlink:title="06261 - Disclosure - Fair Value Measurement (Details 1)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetails" xlink:title="0629 - Disclosure - Financial Information for Parent Guarantor, Other Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_EquityAccountForSubsidiaries" xlink:label="wsh_EquityAccountForSubsidiaries" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="wsh_EquityAccountForSubsidiaries" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:label="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" order="40" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_ProfitLoss" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InterestExpense" xlink:label="us-gaap_InterestExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="us-gaap_InterestExpense" order="80" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InvestmentIncomeDividend" xlink:label="loc_InvestmentIncomeDividend" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="loc_InvestmentIncomeDividend" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="us-gaap_OperatingIncomeLoss" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotesAndWriteOffOfUnamortizedDebtIssuanceCosts" xlink:label="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotesAndWriteOffOfUnamortizedDebtIssuanceCosts_2" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotesAndWriteOffOfUnamortizedDebtIssuanceCosts_2" order="70" use="optional" weight="-1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetails1" xlink:title="062901 - Disclosure - Financial Information for Parent Guarantor, Other Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details 1)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AssetsNoncurrent" xlink:label="us-gaap_AssetsNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_AssetsNoncurrent" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RelatedPartyTransactionDueFromToRelatedParty" xlink:label="loc_RelatedPartyTransactionDueFromToRelatedParty" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="loc_RelatedPartyTransactionDueFromToRelatedParty" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:label="loc_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="loc_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_AssetsCurrent" order="20" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetails2" xlink:title="062902 - Disclosure - Financial Information for Parent Guarantor, Other Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details 2)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromUnsecuredLinesOfCredit" xlink:label="us-gaap_ProceedsFromUnsecuredLinesOfCredit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromUnsecuredLinesOfCredit" order="220" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromIssuanceOfMediumTermNotes" xlink:label="us-gaap_ProceedsFromIssuanceOfMediumTermNotes" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromIssuanceOfMediumTermNotes" order="200" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsOfDebtIssuanceCosts" xlink:label="loc_PaymentsOfDebtIssuanceCosts" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="loc_PaymentsOfDebtIssuanceCosts" order="180" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RepaymentsOfOtherDebt" xlink:label="us-gaap_RepaymentsOfOtherDebt" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_RepaymentsOfOtherDebt" order="160" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="120" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_RelatedPartyTransactionAmountReceivedFromPaidToRelatedParty" xlink:label="wsh_RelatedPartyTransactionAmountReceivedFromPaidToRelatedParty" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="wsh_RelatedPartyTransactionAmountReceivedFromPaidToRelatedParty" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock" xlink:label="us-gaap_PaymentsOfDividendsCommonStock" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsOfDividendsCommonStock" order="60" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries" xlink:label="us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries" order="40" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsOfDividendsMinorityInterest" xlink:label="us-gaap_PaymentsOfDividendsMinorityInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsOfDividendsMinorityInterest" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotes" xlink:label="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotes" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="wsh_MakeWholeOnRepurchaseAndRedemptionOfSeniorNotes" order="170" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ProceedsFromIssueOfLongTermDebt" xlink:label="wsh_ProceedsFromIssueOfLongTermDebt" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="wsh_ProceedsFromIssueOfLongTermDebt" order="50" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/IncomeTaxes" xlink:title="0207 - Disclosure - Income Taxes" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/IncomeTaxesTables" xlink:title="0507 - Disclosure - Income Taxes (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/IncomeTaxesDetails" xlink:title="0607 - Disclosure - Income Taxes (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_IncomeTaxExpenseBenefit" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="loc_DeferredIncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_IncomeTaxExpenseBenefit" xlink:to="loc_DeferredIncomeTaxExpenseBenefit" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DeferredOtherJurisdictionsTaxExpenseBenefit" xlink:label="wsh_DeferredOtherJurisdictionsTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredIncomeTaxExpenseBenefit" xlink:to="wsh_DeferredOtherJurisdictionsTaxExpenseBenefit" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredForeignIncomeTaxExpenseBenefit" xlink:label="loc_DeferredForeignIncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredIncomeTaxExpenseBenefit" xlink:to="loc_DeferredForeignIncomeTaxExpenseBenefit" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:label="loc_DeferredStateAndLocalIncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredIncomeTaxExpenseBenefit" xlink:to="loc_DeferredStateAndLocalIncomeTaxExpenseBenefit" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:label="loc_DeferredFederalIncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredIncomeTaxExpenseBenefit" xlink:to="loc_DeferredFederalIncomeTaxExpenseBenefit" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NonCurrentIncomeTaxExpenseBenefit" xlink:label="wsh_NonCurrentIncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_IncomeTaxExpenseBenefit" xlink:to="wsh_NonCurrentIncomeTaxExpenseBenefit" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NonCurrentOtherJurisdictionsTaxExpenseBenefit" xlink:label="wsh_NonCurrentOtherJurisdictionsTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NonCurrentIncomeTaxExpenseBenefit" xlink:to="wsh_NonCurrentOtherJurisdictionsTaxExpenseBenefit" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NonCurrentStateAndLocalTaxExpenseBenefit" xlink:label="wsh_NonCurrentStateAndLocalTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NonCurrentIncomeTaxExpenseBenefit" xlink:to="wsh_NonCurrentStateAndLocalTaxExpenseBenefit" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NonCurrentFederalTaxExpenseBenefit" xlink:label="wsh_NonCurrentFederalTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NonCurrentIncomeTaxExpenseBenefit" xlink:to="wsh_NonCurrentFederalTaxExpenseBenefit" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:label="loc_CurrentIncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_IncomeTaxExpenseBenefit" xlink:to="loc_CurrentIncomeTaxExpenseBenefit" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_CurrentForeignCountryOneTaxExpenseBenefit" xlink:label="wsh_CurrentForeignCountryOneTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_CurrentIncomeTaxExpenseBenefit" xlink:to="wsh_CurrentForeignCountryOneTaxExpenseBenefit" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit" xlink:label="loc_CurrentFederalTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_CurrentIncomeTaxExpenseBenefit" xlink:to="loc_CurrentFederalTaxExpenseBenefit" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:label="loc_CurrentStateAndLocalTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_CurrentIncomeTaxExpenseBenefit" xlink:to="loc_CurrentStateAndLocalTaxExpenseBenefit" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_CurrentOtherJurisdictionsTaxExpenseBenefit" xlink:label="wsh_CurrentOtherJurisdictionsTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_CurrentIncomeTaxExpenseBenefit" xlink:to="wsh_CurrentOtherJurisdictionsTaxExpenseBenefit" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CurrentForeignTaxExpenseBenefit" xlink:label="loc_CurrentForeignTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_CurrentIncomeTaxExpenseBenefit" xlink:to="loc_CurrentForeignTaxExpenseBenefit" order="80" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NonCurrentForeignIncomeTaxExpenseBenefit" xlink:label="wsh_NonCurrentForeignIncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NonCurrentIncomeTaxExpenseBenefit" xlink:to="wsh_NonCurrentForeignIncomeTaxExpenseBenefit" order="50" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SegmentInformationDetailsTextual" xlink:title="062705 - Disclosure - Segment Information (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/StatementsOfChangesInEquityAndComprehensiveIncome" xlink:title="0140 - Statement - Consolidated Statements of Changes in Equity and Comprehensive Income" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/Employees" xlink:title="0203 - Disclosure - Employees" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ShareBasedCompensation" xlink:title="0204 - Disclosure - Share-Based Compensation" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/AuditorsRemuneration" xlink:title="0205 - Disclosure - Auditors' Remuneration">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/NetLossGainOnDisposalOfOperations" xlink:title="0206 - Disclosure - Net Gain (Loss) on Disposal of Operations" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FiduciaryAssets" xlink:title="0210 - Disclosure - Fiduciary assets">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FixedAssetsNet" xlink:title="0211 - Disclosure - Fixed Assets, Net" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/InvestmentsInAssociates" xlink:title="0214 - Disclosure - Investments in Associates">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/AllowanceForDoubtfulAccounts" xlink:title="0217 - Disclosure - Allowance for Doubtful Accounts">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ProvisionsForLiabilities" xlink:title="0220 - Disclosure - Provisions for Liabilities">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/AccumulatedOtherComprehensiveLossNetOfTax" xlink:title="0222 - Disclosure - Accumulated Other Comprehensive Loss, Net of Tax" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SubsidiaryUndertakings" xlink:title="0228 - Disclosure - Subsidiary Undertakings">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/QuarterlyFinancialDataUnaudited" xlink:title="0231 - Disclosure - Quarterly Financial Data (Unaudited)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/BasisOfPresentationAndSignificantAccountingPoliciesTables" xlink:title="0502 - Disclosure - Basis of Presentation and Significant Accounting Policies (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/BasisOfPresentationAndSignificantAccountingPoliciesDetailsTextual" xlink:title="0602 - Disclosure - Basis of Presentation and Significant Accounting Policies (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EmployeesTables" xlink:title="0503 - Disclosure - Employees (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EmployeesDetails" xlink:title="0603 - Disclosure - Employees (Details)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EmployeesDetailsOne" xlink:title="06032 - Disclosure - Employees (Details 2)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EmployeesDeltailsTextual" xlink:title="06034 - Disclosure - Employees (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ShareBasedCompensationDetails" xlink:title="0604 - Disclosure - Share-Based Compensation (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ShareBasedCompensationDetails1" xlink:title="06041 - Disclosure - Share-Based Compensation (Details 1)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ShareBasedCompensationTables" xlink:title="0504 - Disclosure - Share-Based Compensation (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ShareBasedCompensationDetailsTextual" xlink:title="06042 - Disclosure - Share-Based Compensation (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/AuditorsRemunerationTables" xlink:title="0505 - Disclosure - Auditors' Remuneration (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/AuditorsRemunerationDetails" xlink:title="0605 - Disclosure - Auditors' Remuneration (Details)">
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NetAuditorsRemuneration" xlink:label="wsh_NetAuditorsRemuneration" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OtherServicesProvidedByGroupAuditors" xlink:label="wsh_OtherServicesProvidedByGroupAuditors" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NetAuditorsRemuneration" xlink:to="wsh_OtherServicesProvidedByGroupAuditors" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_AuditRelatedFees" xlink:label="wsh_AuditRelatedFees" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NetAuditorsRemuneration" xlink:to="wsh_AuditRelatedFees" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_AuditFees" xlink:label="wsh_AuditFees" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_NetAuditorsRemuneration" xlink:to="wsh_AuditFees" order="20" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/NetLossGainOnDisposalOfOperationsTables" xlink:title="0506 - Disclosure - Net Gain (Loss) on Disposal of Operations (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/NetLossGainOnDisposalOfOperationsDetails" xlink:title="0606 - Disclosure - Net Gain (Loss) on Disposal of Operations (Details)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax" xlink:label="loc_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromDivestitureOfBusinesses" xlink:label="loc_ProceedsFromDivestitureOfBusinesses" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax" xlink:to="loc_ProceedsFromDivestitureOfBusinesses" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_AssetsDisposedNet" xlink:label="wsh_AssetsDisposedNet" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax" xlink:to="wsh_AssetsDisposedNet" order="10" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_InterestInLiabilities" xlink:label="wsh_InterestInLiabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax" xlink:to="wsh_InterestInLiabilities" order="5" use="optional" weight="-1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/NetLossGainOnDisposalOfOperationsDetailsTextual" xlink:title="06061 - Disclosure - Net Gain (Loss) on Disposal of Operations (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/IncomeTaxesDetails1" xlink:title="06071 - Disclosure - Income Taxes (Details 1)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:label="loc_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="loc_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_MovementInProvisionForNonCurrentTaxes" xlink:label="wsh_MovementInProvisionForNonCurrentTaxes" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="wsh_MovementInProvisionForNonCurrentTaxes" order="60" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ReleaseOfProvisionForUnremittedEarnings" xlink:label="wsh_ReleaseOfProvisionForUnremittedEarnings" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="wsh_ReleaseOfProvisionForUnremittedEarnings" order="80" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxEffectsAllocatedDirectlyToEquityPriorPeriodAdjustment" xlink:label="loc_IncomeTaxEffectsAllocatedDirectlyToEquityPriorPeriodAdjustment" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="loc_IncomeTaxEffectsAllocatedDirectlyToEquityPriorPeriodAdjustment" order="120" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NonDeductibleForeignExchangeLoss" xlink:label="wsh_NonDeductibleForeignExchangeLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="wsh_NonDeductibleForeignExchangeLoss" order="140" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_NonTaxableProfitOnDisposalOfDiscontinuedOperations" xlink:label="wsh_NonTaxableProfitOnDisposalOfDiscontinuedOperations" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="wsh_NonTaxableProfitOnDisposalOfDiscontinuedOperations" order="160" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_EffectOfForeignExchangeDifferences" xlink:label="wsh_EffectOfForeignExchangeDifferences" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="wsh_EffectOfForeignExchangeDifferences" order="180" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OtherJurisdictionsAndDomesticStateTaxes" xlink:label="wsh_OtherJurisdictionsAndDomesticStateTaxes" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="wsh_OtherJurisdictionsAndDomesticStateTaxes" order="240" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:label="loc_IncomeTaxReconciliationOtherAdjustments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="loc_IncomeTaxReconciliationOtherAdjustments" order="190" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpense" xlink:label="loc_IncomeTaxReconciliationNondeductibleExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="loc_IncomeTaxReconciliationNondeductibleExpense" order="10" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate" xlink:label="loc_IncomeTaxReconciliationChangeInEnactedTaxRate" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="loc_IncomeTaxReconciliationChangeInEnactedTaxRate" order="90" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ForeignEarnings" xlink:label="wsh_ForeignEarnings" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="wsh_ForeignEarnings" order="260" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="loc_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="loc_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" order="227.5" use="optional" weight="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/IncomeTaxesDetails2" xlink:title="06072 - Disclosure - Income Taxes (Details 2)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:label="loc_DeferredTaxAssetsLiabilitiesNet" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:label="loc_DeferredTaxLiabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsLiabilitiesNet" xlink:to="loc_DeferredTaxLiabilities" order="40" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesOther" xlink:label="loc_DeferredTaxLiabilitiesOther" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxLiabilities" xlink:to="loc_DeferredTaxLiabilitiesOther" order="160" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesDerivatives" xlink:label="loc_DeferredTaxLiabilitiesDerivatives" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxLiabilities" xlink:to="loc_DeferredTaxLiabilitiesDerivatives" order="140" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:label="loc_DeferredTaxLiabilitiesLeasingArrangements" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxLiabilities" xlink:to="loc_DeferredTaxLiabilitiesLeasingArrangements" order="120" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DeferredTaxLiabilitiesCashRetentionAward" xlink:label="wsh_DeferredTaxLiabilitiesCashRetentionAward" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxLiabilities" xlink:to="wsh_DeferredTaxLiabilitiesCashRetentionAward" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesTaxDeferredIncome" xlink:label="loc_DeferredTaxLiabilitiesTaxDeferredIncome" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxLiabilities" xlink:to="loc_DeferredTaxLiabilitiesTaxDeferredIncome" order="80" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:label="loc_DeferredTaxLiabilitiesPropertyPlantAndEquipment" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxLiabilities" xlink:to="loc_DeferredTaxLiabilitiesPropertyPlantAndEquipment" order="40" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:label="loc_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxLiabilities" xlink:to="loc_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" order="20" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsNet" xlink:label="loc_DeferredTaxAssetsNet" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsLiabilitiesNet" xlink:to="loc_DeferredTaxAssetsNet" order="20" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="loc_DeferredTaxAssetsValuationAllowance" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsNet" xlink:to="loc_DeferredTaxAssetsValuationAllowance" order="40" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsGross" xlink:label="loc_DeferredTaxAssetsGross" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsNet" xlink:to="loc_DeferredTaxAssetsGross" order="20" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DeferredTaxAssetsStockOptions" xlink:label="wsh_DeferredTaxAssetsStockOptions" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsGross" xlink:to="wsh_DeferredTaxAssetsStockOptions" order="140" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" xlink:label="loc_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsGross" xlink:to="loc_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" order="120" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits" xlink:label="loc_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsGross" xlink:to="loc_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits" order="100" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DeferredTaxAssetsForeignCapitalLosses" xlink:label="wsh_DeferredTaxAssetsForeignCapitalLosses" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsGross" xlink:to="wsh_DeferredTaxAssetsForeignCapitalLosses" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DeferredTaxAssetsOtherNetOperatingLosses" xlink:label="wsh_DeferredTaxAssetsOtherNetOperatingLosses" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsGross" xlink:to="wsh_DeferredTaxAssetsOtherNetOperatingLosses" order="160" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign" xlink:label="loc_DeferredTaxAssetsOperatingLossCarryforwardsForeign" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsGross" xlink:to="loc_DeferredTaxAssetsOperatingLossCarryforwardsForeign" order="60" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic" xlink:label="loc_DeferredTaxAssetsOperatingLossCarryforwardsDomestic" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsGross" xlink:to="loc_DeferredTaxAssetsOperatingLossCarryforwardsDomestic" order="40" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_AccruedExpensesNotCurrentlyDeductible" xlink:label="wsh_AccruedExpensesNotCurrentlyDeductible" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsGross" xlink:to="wsh_AccruedExpensesNotCurrentlyDeductible" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPrepaidPensionCosts" xlink:label="loc_DeferredTaxLiabilitiesPrepaidPensionCosts" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxLiabilities" xlink:to="loc_DeferredTaxLiabilitiesPrepaidPensionCosts" order="70" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal" xlink:label="loc_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsGross" xlink:to="loc_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal" order="30" use="optional" weight="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/IncomeTaxesDetails2Alternate" xlink:title="060721 - Disclosure - Income Taxes (Details 2) (Alternate)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:label="loc_DeferredTaxAssetsLiabilitiesNet" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent" xlink:label="loc_DeferredTaxAssetsLiabilitiesNetNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsLiabilitiesNet" xlink:to="loc_DeferredTaxAssetsLiabilitiesNetNoncurrent" order="20" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:label="us-gaap_DeferredTaxLiabilitiesNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsLiabilitiesNetNoncurrent" xlink:to="us-gaap_DeferredTaxLiabilitiesNoncurrent" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsNetNoncurrent" xlink:label="us-gaap_DeferredTaxAssetsNetNoncurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsLiabilitiesNetNoncurrent" xlink:to="us-gaap_DeferredTaxAssetsNetNoncurrent" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNetCurrent" xlink:label="loc_DeferredTaxAssetsLiabilitiesNetCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsLiabilitiesNet" xlink:to="loc_DeferredTaxAssetsLiabilitiesNetCurrent" order="40" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxLiabilitiesCurrent" xlink:label="us-gaap_DeferredTaxLiabilitiesCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsLiabilitiesNetCurrent" xlink:to="us-gaap_DeferredTaxLiabilitiesCurrent" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredTaxAssetsNetCurrent" xlink:label="us-gaap_DeferredTaxAssetsNetCurrent" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DeferredTaxAssetsLiabilitiesNetCurrent" xlink:to="us-gaap_DeferredTaxAssetsNetCurrent" order="40" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/IncomeTaxesDetails3" xlink:title="06073 - Disclosure - Income Taxes (Details 3)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/IncomeTaxesDetails4" xlink:title="06074 - Disclosure - Income Taxes (Details 4)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/IncomeTaxesDetailsTextual" xlink:title="06075 - Disclosure - Income Taxes (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FiduciaryAssetsDetails" xlink:title="0610 - Disclosure - Fiduciary Assets (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FixedAssetsNetTables" xlink:title="0511 - Disclosure - Fixed Assets, Net (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FixedAssetsNetDetails" xlink:title="0611 - Disclosure - Fixed Assets, Net (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FixedAssetsNetDetailsTextual" xlink:title="06111 - Disclosure - Fixed Assets, Net (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/InvestmentsInAssociatesTables" xlink:title="0513 - Disclosure - Investments in Associates (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/InvestmentsInAssociatesDetails" xlink:title="0614 - Disclosure - Investments in Associates (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/InvestmentsInAssociatesDetails1" xlink:title="06141 - Disclosure - Investments in Associates (Details 1)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_EquityMethodInvestmentSummarizedFinancialInformationEquity" xlink:label="loc_EquityMethodInvestmentSummarizedFinancialInformationEquity" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAssets" xlink:label="loc_EquityMethodInvestmentSummarizedFinancialInformationAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_EquityMethodInvestmentSummarizedFinancialInformationEquity" xlink:to="loc_EquityMethodInvestmentSummarizedFinancialInformationAssets" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_EquityMethodInvestmentSummarizedFinancialInformationLiabilities" xlink:label="loc_EquityMethodInvestmentSummarizedFinancialInformationLiabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_EquityMethodInvestmentSummarizedFinancialInformationEquity" xlink:to="loc_EquityMethodInvestmentSummarizedFinancialInformationLiabilities" order="40" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/InvestmentsInAssociatesDetailsTextual" xlink:title="06142 - Disclosure - Investments In Associates (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/AllowanceForDoubtfulAccountsTables" xlink:title="0516 - Disclosure - Allowance for Doubtful Accounts (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/AllowanceForDoubtfulAccountsDetails" xlink:title="0617 - Disclosure - Allowance for Doubtful Accounts (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails1" xlink:title="061801 - Disclosure - Pension Plans (Details 1)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails2" xlink:title="061802 - Disclosure - Pension Plans (Details 2)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostNetOfTax" xlink:label="loc_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostNetOfTax" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="loc_DefinedBenefitPlanNetPeriodicBenefitCost" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostNetOfTax" xlink:to="loc_DefinedBenefitPlanNetPeriodicBenefitCost" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" xlink:label="loc_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:to="loc_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" order="20" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="loc_DefinedBenefitPlanServiceCost" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:to="loc_DefinedBenefitPlanServiceCost" order="40" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="loc_DefinedBenefitPlanInterestCost" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:to="loc_DefinedBenefitPlanInterestCost" order="60" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:label="loc_DefinedBenefitPlanExpectedReturnOnPlanAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:to="loc_DefinedBenefitPlanExpectedReturnOnPlanAssets" order="80" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfNetGainsLosses" xlink:label="loc_DefinedBenefitPlanAmortizationOfNetGainsLosses" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:to="loc_DefinedBenefitPlanAmortizationOfNetGainsLosses" order="100" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments" xlink:label="loc_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:to="loc_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments" order="120" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" xlink:label="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostNetOfTax" xlink:to="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" order="40" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostBeforeTax" xlink:label="loc_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostBeforeTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" xlink:to="loc_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostBeforeTax" order="20" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OtherComprehensiveIncomeLossReclassificationPensionAndOtherPostretirementBenefitPlansAmortizationOfUnrecognizedActuarialLossInNetPeriodicBenefitCostNetOfTax" xlink:label="wsh_OtherComprehensiveIncomeLossReclassificationPensionAndOtherPostretirementBenefitPlansAmortizationOfUnrecognizedActuarialLossInNetPeriodicBenefitCostNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" xlink:to="wsh_OtherComprehensiveIncomeLossReclassificationPensionAndOtherPostretirementBenefitPlansAmortizationOfUnrecognizedActuarialLossInNetPeriodicBenefitCostNetOfTax" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeAmortizationOfDefinedBenefitPlanNetPriorServiceCostCreditRecognizedInNetPeriodicBenefitCostBeforeTax" xlink:label="loc_OtherComprehensiveIncomeAmortizationOfDefinedBenefitPlanNetPriorServiceCostCreditRecognizedInNetPeriodicBenefitCostBeforeTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" xlink:to="loc_OtherComprehensiveIncomeAmortizationOfDefinedBenefitPlanNetPriorServiceCostCreditRecognizedInNetPeriodicBenefitCostBeforeTax" order="60" use="optional" weight="-1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OtherComprehensiveIncomeLossAmortizationPensionAndOtherPostretirementBenefitPlansNetPriorServiceCostCreditUnrecognizedInNetPeriodicBenefitCostBeforeTax" xlink:label="wsh_OtherComprehensiveIncomeLossAmortizationPensionAndOtherPostretirementBenefitPlansNetPriorServiceCostCreditUnrecognizedInNetPeriodicBenefitCostBeforeTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" xlink:to="wsh_OtherComprehensiveIncomeLossAmortizationPensionAndOtherPostretirementBenefitPlansNetPriorServiceCostCreditUnrecognizedInNetPeriodicBenefitCostBeforeTax" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansCurtailmentTaxEffect" xlink:label="loc_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansCurtailmentTaxEffect" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" xlink:to="loc_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansCurtailmentTaxEffect" order="100" use="optional" weight="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails3" xlink:title="061803 - Disclosure - Pension Plans (Details 3)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails4" xlink:title="061804 - Disclosure - Pension Plans (Details 4)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDtails5" xlink:title="061805 - Disclosure - Pension Plans (Details 5)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:label="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanEquitySecurities" xlink:label="loc_DefinedBenefitPlanEquitySecurities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:to="loc_DefinedBenefitPlanEquitySecurities" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanDebtSecurities" xlink:label="loc_DefinedBenefitPlanDebtSecurities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:to="loc_DefinedBenefitPlanDebtSecurities" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanOtherPlanAssets" xlink:label="loc_DefinedBenefitPlanOtherPlanAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:to="loc_DefinedBenefitPlanOtherPlanAssets" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanRealEstate" xlink:label="loc_DefinedBenefitPlanRealEstate" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:to="loc_DefinedBenefitPlanRealEstate" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DefinedBenefitPlanCash" xlink:label="wsh_DefinedBenefitPlanCash" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:to="wsh_DefinedBenefitPlanCash" order="100" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails6" xlink:title="061806 - Disclosure - Pension Plans (Details 6)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails7" xlink:title="061808 - Disclosure - Pension Plans (Details 8)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetailsEight" xlink:title="061809 - Disclosure - Pension Plans (Details 9)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_2" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="us-gaap_DefinedBenefitPlanServiceCost_2" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_2" xlink:to="us-gaap_DefinedBenefitPlanServiceCost_2" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="us-gaap_DefinedBenefitPlanInterestCost_2" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_2" xlink:to="us-gaap_DefinedBenefitPlanInterestCost_2" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:label="loc_DefinedBenefitPlanExpectedReturnOnPlanAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_2" xlink:to="loc_DefinedBenefitPlanExpectedReturnOnPlanAssets" order="60" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfNetGainsLosses" xlink:label="loc_DefinedBenefitPlanAmortizationOfNetGainsLosses" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_2" xlink:to="loc_DefinedBenefitPlanAmortizationOfNetGainsLosses" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments" xlink:label="loc_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_2" xlink:to="loc_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments" order="100" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DefinedBenefitPlanOther" xlink:label="wsh_DefinedBenefitPlanOther" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_2" xlink:to="wsh_DefinedBenefitPlanOther" order="120" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostNetOfTax" xlink:label="loc_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostNetOfTax" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" xlink:label="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostNetOfTax" xlink:to="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostBeforeTax" xlink:label="loc_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostBeforeTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" xlink:to="loc_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostBeforeTax" order="20" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_OtherComprehensiveIncomeLossReclassificationPensionAndOtherPostretirementBenefitPlansAmortizationOfUnrecognizedActuarialLossInNetPeriodicBenefitCostNetOfTax" xlink:label="wsh_OtherComprehensiveIncomeLossReclassificationPensionAndOtherPostretirementBenefitPlansAmortizationOfUnrecognizedActuarialLossInNetPeriodicBenefitCostNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetGainLossBeforeTax" xlink:to="wsh_OtherComprehensiveIncomeLossReclassificationPensionAndOtherPostretirementBenefitPlansAmortizationOfUnrecognizedActuarialLossInNetPeriodicBenefitCostNetOfTax" order="40" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetailsNine" xlink:title="061810 - Disclosure - Pension Plans (Details 10)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetailsTen" xlink:title="061811 - Disclosure - Pension Plans (Details 11)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:label="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanEquitySecurities" xlink:label="loc_DefinedBenefitPlanEquitySecurities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:to="loc_DefinedBenefitPlanEquitySecurities" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanDebtSecurities" xlink:label="loc_DefinedBenefitPlanDebtSecurities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:to="loc_DefinedBenefitPlanDebtSecurities" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanRealEstate" xlink:label="loc_DefinedBenefitPlanRealEstate" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:to="loc_DefinedBenefitPlanRealEstate" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanOtherPlanAssets" xlink:label="loc_DefinedBenefitPlanOtherPlanAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:to="loc_DefinedBenefitPlanOtherPlanAssets" order="80" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetailsTextual" xlink:title="061815 - Disclosure - Pension Plans (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/AccumulatedOtherComprehensiveLossNetOfTaxDetailsTextual" xlink:title="06222 - Disclosure - Accumulated Other Comprehensive Loss, Net of Tax (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EarningsPerShareDetailsTextual" xlink:title="06091 - Disclosure - Earnings Per Share (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails11" xlink:title="061807 - Disclosure - Pension Plans (Details 7)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails12" xlink:title="061812 - Disclosure - Pension Plans (Details 12)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails13" xlink:title="061813 - Disclosure - Pension Plans (Details 13)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/PensionPlansDetails14" xlink:title="061814 - Disclosure - Pension Plans (Details 14)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ProvisionsForLiabilitiesTables" xlink:title="0520 - Disclosure - Provisions for Liabilities (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/ProvisionsForLiabilitiesDetails" xlink:title="0620 - Disclosure - Provisions for Liabilities (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/CommitmentsAndContingenciesTables" xlink:title="0521 - Disclosure - Commitments and Contingencies (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/CommitmentsAndContingenciesDetails1" xlink:title="0621 - Disclosure - Commitments and Contingencies (Details)">
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationPayments" xlink:label="wsh_ContractualObligationPayments" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentAfterFiveYears" xlink:label="wsh_ContractualObligationsDueForRepaymentAfterFiveYears" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentAfterFiveYears" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentInYearsFourAndFive" xlink:label="wsh_ContractualObligationsDueForRepaymentInYearsFourAndFive" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentInYearsFourAndFive" order="10" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentInYearsTwoAndThree" xlink:label="wsh_ContractualObligationsDueForRepaymentInYearsTwoAndThree" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentInYearsTwoAndThree" order="5" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentInNextTwelveMonths" xlink:label="wsh_ContractualObligationsDueForRepaymentInNextTwelveMonths" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentInNextTwelveMonths" order="2.5" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/CommitmentsAndContingenciesDetails2" xlink:title="06211 - Disclosure - Commitments and Contingencies (Details 1)">
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationPayments" xlink:label="wsh_ContractualObligationPayments" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentAfterFiveYears" xlink:label="wsh_ContractualObligationsDueForRepaymentAfterFiveYears" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentAfterFiveYears" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentInYearFive" xlink:label="wsh_ContractualObligationsDueForRepaymentInYearFive" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentInYearFive" order="40" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentInYearFour" xlink:label="wsh_ContractualObligationsDueForRepaymentInYearFour" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentInYearFour" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentInYearThree" xlink:label="wsh_ContractualObligationsDueForRepaymentInYearThree" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentInYearThree" order="80" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentInYearTwo" xlink:label="wsh_ContractualObligationsDueForRepaymentInYearTwo" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentInYearTwo" order="100" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_ContractualObligationsDueForRepaymentInNextTwelveMonths" xlink:label="wsh_ContractualObligationsDueForRepaymentInNextTwelveMonths" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_ContractualObligationPayments" xlink:to="wsh_ContractualObligationsDueForRepaymentInNextTwelveMonths" order="120" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/CommitmentsAndContingenciesDetailsTextual" xlink:title="06212 - Disclosure - Commitments and Contingencies (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/CommitmentsAndContingenciesAlternativeDetails1" xlink:title="062011 - Disclosure - Commitments and Contingencies (Alternative) (Details 1)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SegmentInformationDetails3" xlink:title="062703 - Disclosure - Segment Information (Details 3)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SegmentInformationDetails4" xlink:title="062704 - Disclosure - Segment Information (Details 4)">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/QuarterlyFinancialDataUnauditedDetails" xlink:title="0631 - Disclosure - Quarterly Financial Data (Unaudited) (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EmployeesDetails2" xlink:title="06031 - Disclosure - Employees (Details 1)">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LaborAndRelatedExpense" xlink:label="us-gaap_LaborAndRelatedExpense" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_SalariesWagesAndOfficersCompensation" xlink:label="loc_SalariesWagesAndOfficersCompensation" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LaborAndRelatedExpense" xlink:to="loc_SalariesWagesAndOfficersCompensation" order="20" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_AllocatedShareBasedCompensationExpense" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LaborAndRelatedExpense" xlink:to="loc_AllocatedShareBasedCompensationExpense" order="40" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_SeveranceCosts" xlink:label="loc_SeveranceCosts" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LaborAndRelatedExpense" xlink:to="loc_SeveranceCosts" order="60" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedContributionPlanCostRecognized" xlink:label="loc_DefinedContributionPlanCostRecognized" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LaborAndRelatedExpense" xlink:to="loc_DefinedContributionPlanCostRecognized" order="140" use="optional" weight="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_SocialSecurityCosts" xlink:label="wsh_SocialSecurityCosts" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LaborAndRelatedExpense" xlink:to="wsh_SocialSecurityCosts" order="70" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="loc_DefinedBenefitPlanNetPeriodicBenefitCost" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LaborAndRelatedExpense" xlink:to="loc_DefinedBenefitPlanNetPeriodicBenefitCost" order="105" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/EmployeesDetails3" xlink:title="06033 - Disclosure - Employees (Details 3)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SubsidiaryUndertakingsTables" xlink:title="0528 - Disclosure - Subsidiary Undertakings (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/SubsidiaryUndertakingsDetails" xlink:title="0628 - Disclosure - Subsidiary Undertakings (Details)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DebtDetailsTextual" xlink:title="061902 - Disclosure - Debt (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DiscontinuedOperations" xlink:title="0208 - Disclosure - Discontinued operations">
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DiscontinuedOperationsDetail" xlink:title="0608 - Disclosure - Discontinued operations (Detail)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DiscontinuedOperationsDetail1" xlink:title="06081 - Disclosure - Discontinued Operations (Detail 1)">
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DisposalGroupIncludingDiscontinuedOperationNetAssetsLiabilityOfDisposalGroup" xlink:label="wsh_DisposalGroupIncludingDiscontinuedOperationNetAssetsLiabilityOfDisposalGroup" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:label="loc_AssetsOfDisposalGroupIncludingDiscontinuedOperation" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_DisposalGroupIncludingDiscontinuedOperationNetAssetsLiabilityOfDisposalGroup" xlink:to="loc_AssetsOfDisposalGroupIncludingDiscontinuedOperation" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets" xlink:label="loc_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:to="loc_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets" order="20" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNet" xlink:label="loc_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNet" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:to="loc_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNet" order="10" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwill" xlink:label="loc_DisposalGroupIncludingDiscontinuedOperationGoodwill" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:to="loc_DisposalGroupIncludingDiscontinuedOperationGoodwill" order="5" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DisposalGroupIncludingDiscontinuedOperationFiduciaryAssets" xlink:label="wsh_DisposalGroupIncludingDiscontinuedOperationFiduciaryAssets" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:to="wsh_DisposalGroupIncludingDiscontinuedOperationFiduciaryAssets" order="2.5" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents" xlink:label="loc_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:to="loc_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents" order="1.25" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" xlink:label="loc_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="wsh_DisposalGroupIncludingDiscontinuedOperationNetAssetsLiabilityOfDisposalGroup" xlink:to="loc_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" order="40" use="optional" weight="-1" priority="1" />
    <loc xlink:type="locator" xlink:href="wsh-20111231.xsd#wsh_DisposalGroupIncludingDiscontinuedOperationFiduciaryLiabilities" xlink:label="wsh_DisposalGroupIncludingDiscontinuedOperationFiduciaryLiabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" xlink:to="wsh_DisposalGroupIncludingDiscontinuedOperationFiduciaryLiabilities" order="10" use="optional" weight="1" priority="1" />
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentLiabilities" xlink:label="loc_DisposalGroupIncludingDiscontinuedOperationOtherCurrentLiabilities" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" xlink:to="loc_DisposalGroupIncludingDiscontinuedOperationOtherCurrentLiabilities" order="20" use="optional" weight="1" priority="1" />
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DiscontinuedOperationsDetailTextual" xlink:title="06082 - Disclosure - Discontinued Operations (Detail Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesDetails5" xlink:title="062501 - Disclosure - Derivative Financial Instruments and Hedging Activities (Details 1)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentIssuerGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetailsTextual" xlink:title="06303 - Disclosure - Financial Information for Parent Issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentGuarantorOtherGuarantorSubsidiariesAndNonGuarantorSubsidiariesDetailsTextual" xlink:title="062903 - Disclosure - Financial Information for Parent Guarantor, Other Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details Textual)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/DiscontinuedOperationTables" xlink:title="0508 - Disclosure - Discontinued Operation (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/QuarterlyFinancialDataUnauditedTables" xlink:title="0531 - Disclosure - Quarterly Financial Data (Unaudited) (Tables)" />
  <calculationLink xlink:type="extended" xlink:role="http://willis.com/role/FinancialInformationForParentIssuerGuarantorSubsidiariesAndNonGuarantorSubsidiariesTables" xlink:title="0530 - Disclosure - Financial Information for Parent Issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Tables)" />
</linkbase>
</XBRL>
