McCann Erickson has leapfrogged the WPP agency to take second place by increasing billings to £305 million -- a growth of 4.5 per cent since the end of last year.
Other agencies to record growth include Bartle Bogle Hegarty, which shot up from seventh to fourth thanks to wins for Vodafone and Procter & Gamble. The agency increased billings by 27 per cent from £212 million to £270 million over the period.
WCRS has moved into the top ten for the first time, after growing billings by 55 per cent from £134 million to £208 million on the back of wins including Sky and Littlewoods. The agency jumped from 17th to 9th.
Will Orr, the managing director at WCRS, said: "Our priority is great strategy and creative work. Our recent growth is a welcome sign that we're delivering on that."
The results also show that Fallon has broken into the top 20 for the first time, moving from 24th to 19th. Last year's Campaign Agency of the Year increased billings from £60 million in December to £113 million in August, representing growth of 88 per cent.
August's data also shows that 2007 has been a tricky time for many network agencies. DDB London fell from 9th to 11th place over the period, while Publicis dropped from 5th to 8th after losing Asda and MFI.
Ogilvy Advertising also fell from 8th to 10th, Leo Burnett from 10th to 12th, Saatchi & Saatchi from 11th to 14th and Grey from 13th to 15th.
The Nielsen league ranks UK agencies by the combined adspend (billings) of their clients.