DUBLIN—Willis Group Holdings P.L.C. said Wednesday that it appointed Michael J. Somers as a director of the brokerage and a member of its risk committee of the board of directors.

Mr. Somers is the former CEO of the Irish National Treasury Management Agency, a post he held from 1990 until the end of 2009. He also previously worked in the Irish Department of Finance and the Central Bank.

Mr. Somers served on the board of the Irish Stock Exchange until the end of 2009 and is Irish director on the board of European Investment Bank Group. He also serves on the boards of Allied Irish Banks P.L.C., St. Vincent’s Healthcare Group Ltd. and the Institute of Directors, and he is a council member of the Dublin Chamber of Commerce.