**EXHIBIT31.1****CERTIFICATION OF THE CHIEF EXECUTIVE OFFICER****PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002**I, Thomas H. Glocer, certify that: 1. I have reviewed this annual report on Form 20-F of Thomson Reuters PLC;  2. Based on my knowledge, this report does not contain any untruestatement of a material fact or omit to state a material fact necessary tomake the statements made, in light of the circumstances under which suchstatements were made, not misleading with respect to the period covered bythis report;  3. Based on my knowledge, the financial statements, and other financialinformation included in this annual report, fairly present in all materialrespects the financial condition, results of operations and cash flows of thecompany as of, and for, the periods presented in this report;  4. The company’s other certifying officer and I are responsible for establishingand maintaining disclosure controls and procedures (as defined in ExchangeAct Rules 13a-15(e) and 15d-15(e)) and internal control over financialreporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for thecompany and have: a) designed such disclosure controlsand procedures, or caused suchdisclosure controls and proceduresto be designed under oursupervision, to ensure thatmaterial information relating tothe company, including itsconsolidated subsidiaries, is madeknown to us by others within thoseentities, particularly during theperiod in which this reportis being prepared;  b) designed such internal control overfinancial reporting, or caused suchinternal control over financialreporting to be designed under oursupervision, to provide reasonableassurance regarding the reliabilityof financial reporting and thepreparation of financial statementsfor external purposes in accordancewith generally accepted accountingprinciples;  c) evaluated the effectiveness of thecompany’s disclosure controls andprocedures and presented in thisreport our conclusions about theeffectiveness of the disclosurecontrols and procedures, as of theend of the period covered by thisreport based on such evaluation;and  d) disclosed in this report any changein the company’s internal controlover financial reporting thatoccurred during the period coveredby the annual report that hasmaterially affected, or isreasonably likely to materiallyaffect, the company’s internalcontrol over financial reporting;and 5. The company’s other certifying officer and I have disclosed, based on ourmost recent evaluation of internal control over financial reporting, to thecompany’s auditors and the audit committee of the company’s board ofdirectors (or persons performing the equivalent functions): a) all significant deficiencies andmaterial weaknesses in the designor operation of internal controlover financial reporting which arereasonably likely to adverselyaffect the company’s ability torecord, process, summarize andreport financial information; and  b) any fraud, whether or not material,that involves management or otheremployees who have a significantrole in the company’s internalcontrol over financial reporting.Date: April 17, 2008         /s/ Thomas H. Glocer   Thomas H. Glocer   Chief Executive Officer