Willis Towers Watson Public Limited (WTW) 8-K 2010 FY Willis Group Holdings Announces Senior Notes Offering

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration StatementsNo. 333-153769 and333-160129 onForm S-3 and in Registration StatementsNo. 333-62780,No. 333-63186,No. 333-130605,No. 333-153202,No. 333-153770 andNo. 333-169961 onForm S-8 of our report dated February 25, 2011 (March 14, 2011 as to Note 30) relating to the consolidated financial statements of Willis Group Holdings Public Limited Company for the year ended December 31, 2010 appearing in this Current Report onForm 8-K of Willis Group Holdings Public Limited Company.

/s/  Deloitte LLP

London, United Kingdom

March 14, 2011

5