The news may strike some in the industry as surprising, given that the ad agency's reputation for creative flair and innovative working practices probably eclipses perceptions of its financial credentials.
However, Mother, which met all eight benchmarks, managed to climb the ranks from sixth place in last year's table to attain first position this year. This makes the agency, which counts Coca-Cola and Orange among its clients, an increasingly attractive takeover prospect for predatory groups.
In second place, Bournemouth-based media agency RLA Media also scored across all criteria, a meteoric rise from last year's 16th place. Bartle Bogle Hegarty maintained third place.
From the direct marketing world, Tullo Marshall Warren came eighth.
The survey measures the performance of unlisted advertising, PR, direct marketing, media buying and digital agencies against eight financial benchmarks.
"The purpose of the league table is to recognise the quality of financial management among the better-run private companies," Bob Willott, the report's author, said. "Not surprisingly, that has lead to several of them being sought and bought in the past year."
Fourteen per cent of last year's top 50 agencies have been snapped up by larger groups, including Miles Calcraft Briginshaw Duffy, PR consultancy Freud, and Face Communications, which owned Delaney Lund Knox Warren.
Overall, the survey shows that the financial quality of the companies featured is improving across the board.
"More privately owned marketing companies achieved consistent income growth and exceeded our £500,000 average operating profit than last year," Willott added. "But the recovery has been slow and the recent industry recession has left its scars.
"Less than one-third of the 50 companies had sufficient working capital to satisfy our fairly demanding criteria or had enjoyed income growth of at least 50% over a two-year period."
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