Fee and commission income (2003): £6547m.

Pre-tax profit (2003): Not supplied

Address: 8 Devonshire Square

London EC2M 4PL

Tel: 020 7623 5500

Fax: 020 7621 1511

Website: www.aon.co.uk

Year established: Aon Ltd was formed in 2001 following the merger of Aon's businesses in the UK. Aon Ltd's parent company, Aon Corporation, was founded in 1982.

History: With its stock traded on the New York stock exchange, Aon has grown steadily since it was founded in 1982, when the Ryan Insurance Group merged with Combined International Corporation. Aon now has more than 55,000 employees with offices in 125 countries around the world.

Throughout the 1980s and 1990s, strategic acquisitions and organic growth fuelled Aon's expansion in the global insurance and human capital consulting marketplace.

Over the past 20 years, Aon has acquired some of the most well-known players in the insurance and consulting industries, many having been notable players in their respective fields for years.

Aon in the UK consists of a close network of companies and business units structured under the single banner of Aon Ltd, each concentrating on specific industries, practice groups, products and services - providing clients with efficient and customised solutions tailored to their specific needs.

Major shareholders: Aon Ltd is a wholly-owned subsidiary of Aon Corporation

Main lines of business: Insurance and reinsurance broking, risk management consulting, human capital consulting, including pensions and investment consulting and HR outsourcing.

Number of UK branches: 50

Number of employees (average for 2003): 7,300

Chief officer: Dennis Mahoney, chairman and chief executive

Biography: As chairman and chief executive officer of Aon Ltd, Dennis Mahoney is responsible for all of Aon's specialist and reinsurance broking operations outside the US, as well as overall co-ordination of Aon operations in the UK.

Prior to assuming this role, Mahoney was chairman and chief executive officer of Aon Group Ltd, the London-based reinsurance and specialist broking operation of Aon Group Inc.

Dennis Mahoney began his insurance career in 1969, when he joined the North American division of Price Forbes & Co.

He was appointed to the board of Sedgwick Ltd in 1982, and in June 1984 he was invited to join Alexander Howden Group as chairman of Alexander Howden Ltd, the London-based wholesale broking arm of Alexander & Alexander Services.

He has also served as a deputy chairman of Lloyd's insurance broking committee and is the current president of the Insurance Institute of London.