At its annual general meeting, where shareholders voted in favour of WPP's executive pay package, the advertising group said factors such as Euro 2004, the Olympics and growth in the US were behind the increase.
Excluding last year's Cordiant acquisition, WPP's revenues rose by 4 per cent over the first five months. It said that media planning and buying was the most buoyant part of its business, with growth in revenues of more than 14 per cent.
UK revenue growth was especially strong, up 12 per cent, against 8 per cent growth in continental Europe. US revenues rose by 10 per cent.
WPP also said that it had reduced its headcount by an average 2 per cent across its businesses while increasing its operating margin to 13.8 per cent.
Philip Lader, WPP's chairman, said that an improvement in WPP's creative was a key goal, to be achieved "by recruiting excellent talent, acquiring outstanding creative businesses, recognising and celebrating creative success and pursuing creative awards".
He added: "Companies in the marketing services sector need to be creative organisations through and through."