Marsh has toppled Aon from the UK's number one broker spot for the first time in nearly 10 years.

According to figures compiled exclusively for Insurance Times Top 50 Brokers, Marsh UK's brokerage rose 13.1% to £658.7m for the year ended December 2004 compared to £582.6m in the previous year.

In contrast, Aon UK's dominance in the market has slipped again this year. Aon plummeted 16.1% in brokerage during 2004, while during 2003 its figure fell 12.9%. Two consecutive years of double-digit decreases has cost it the UK broker crown. Its brokerage for 2004 is £549.4m, down from £654.7m in 2003.

These figures are a bitter sweet reminder to the UK management at Marsh, led by president and chief executive of Marsh's Europe/Middle East Operations Bruce Carnegie-Brown, of the impact of Eliot Spitzer's inquiry into the broker.

The figures do not encapsulate the full impact of the contingent commission debacle, but the £100m difference between Marsh and Aon reflects the inroads Marsh had made into Aon's traditional retail market.

Commenting on Marsh's achievement, Carnegie-Brown said: "It would be impossible not to be pleased with this result during the best of times. Given the environment in which it was produced, however, this is a strong tribute to the professionalism and resilience of our colleagues and their continued focus on our clients."

Oliver Laughton-Scott of IMAS corporate advisers, which compiled the Top 50 Brokers list, said: "The switch between Marsh and Aon is symptomatic of wider changes in the Top 50 this year after a number of years of relatively little change. Individual company performances are showing far greater variability than before ."

' The Top 50 Brokers will be published next month