<Page> EXHIBIT 23.1 [Letterhead of Deloitte & Touche] INDEPENDENT AUDITORS' CONSENT We consent to the incorporation by reference in this Registration Statement on Form S-8 of our report on Willis Group Holdings Limited dated February 13, 2001, except for Notes 1 and 21, as to which the date is October 29, 2001, which appears in Amendment No. 2 to Registration Statement No. 333-72459 of Willis Group Holdings Limited on Form F-1 dated November 8, 2001. /s/ Deloitte & Touche DELOITTE & TOUCHE November 21, 2001