LONDON, 17 July 2008 - Aon announces the appointment of Mark Chessher to the position of CFO of Aon Limited and ARS (UK).

Mark will join the company later in the year, subject to FSA approval and will sit on the Aon Limited board. He replaces John Cullen, who earlier this year was promoted to the role of global CFO for Aon Risk Services.

Mark joins Aon from Zurich Financial Services, where he is currently CFO of their North American large corporate customer division based in New York.  Prior to this he was Zurich's UK Finance Director for two years. Mark also served five years in Zurich's US Personal Lines operation based in Los Angeles. He has also worked for KPMG in London and in Sydney, Australia. 

Peter Harmer, CEO of Aon Limited, comments: "Mark brings to Aon a sound knowledge of the insurance industry, along with five years of experience of interacting with the FSA. He joins us in a challenging market and at a time of change, bringing with him a set of skills and experience that are well suited to helping us successfully implement our growth strategy."

Mark is a Chartered Accountant and an Associate of the Chartered Insurance Institute.

For more information contact:
Reuben Aitchison
020 7086 7201
reuben.aitchison@aon.co.uk
http://aon.mediaroom.com

About Aon
Aon Corporation (NYSE: AOC) is the leading global provider of risk management services, insurance and reinsurance brokerage, human capital and management consulting. Through its 36,000 colleagues worldwide, Aon readily delivers distinctive client value via innovative and effective risk management and workforce productivity solutions. Our industry-leading global resources, technical expertise and industry knowledge are delivered locally through more than 500 offices in more than 120 countries. Aon was named the world's "best broker" by Euromoney magazine's 2008 Insurance Survey. Aon also was ranked by A.M. Best as the number one global insurance brokerage in 2007 based on brokerage revenues, and voted best insurance intermediary, best reinsurance intermediary, and best employee benefits consulting firm in 2007 by the readers of Business Insurance. For more information on Aon, log onto www.aon.com

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