Willis has overtaken Marsh as the second largest broker in the UK, just behind number one broker Aon, according to the Insurance Times' annual Top 50 Brokers guide.
The listing, produced by corporate adviser IMAS exclusively for Insurance Times, shows that Willis disclosed a brokerage of £717m, compared to Marsh's disclosed brokerage of £554m.
Willis, which almost doubled its disclosed brokerage from the 2002 list, is now just behind Aon which disclosed a fee and commission income of £731m.
The list - free with this issue of Insurance Times - reveals an average income growth of 20% across the whole top 50. That is one of the biggest rises ever.
According to IMAS analyst Oliver Laughton-Scott, two-thirds of the growth has come organically, with just one-third through acquisition.
Further down the listing, the fastest growing company is Thompson Heath Bond followed by Budget, AJ Gallagher and RK Harrison.
Significant new entrants to the Insurance Times top 50 include The Folgate Partnership which entered the list at 21 and Tyser, which was recently incorporated and therefore filed its first results in time to be included on the list.
The number of fat cat brokers is increasing following bumper results. From last year's list, only one director was paid more than £1m. This year the number has risen to five.
Sector-by-sector, commercial lines registered the biggest growth with a 31% rise in brokerage. London Market business brokerage rose 18% and personal lines business rose 16%.
Of the big personal lines brokers, the AA continues to lead the field at number eight, with Swinton, HHH and Budget coming in at ten, 11 and 12 respectively. Endsleigh maintained a solid 15th spot and Hastings came in at 18.
The exclusive top 50 listing has changed from last year. All distributors dealing with sole suppliers have been dropped from the list - this includes Lloyds TSB, Barclays and Saga among others.