Former WPP boss Martin Sorrell buys Dutch digital agency

Sir Martin Sorrell has beaten his former employer WPP (Frankfurt: A1J2BZ - news) to buy Dutch digital agency MediaMonks for an undisclosed sum.

Mr Sorrell's S4 Capital had taken on WPP in a bitter battle to take control of the Dutch company, thought to be worth €300m (£265m).

WPP, the FTSE 100 company he found, warned Mr. Sorrell that his bid was " unlawful" and it would strip him of his WPP shares worth £20m .

WPP alleged Mr Sorrell had been "heavily engaged" in WPP's evaluation of the bid for MediaMonks. Mr Sorrell , who left the company in April, disputed those claims and asked WPP to provide evidence of his involvement.

Sir Martin's new vehicle, S4 Capital, has lined up funding from a consortium of City investors to acquire MediaMonks, which counts Audi (IOB: 0FG8.IL - news) and Lego among its clients.

The shareholders of MediaMonks, which has revenues of €110m, will receive cash and shares in S4 Capital.

S4 Capital has been created from a reverse takeover of Derriston Capital, a listed cash shell, that Sir Martin plans to use it as a vehicle to build a "next-generation" marketing services group.

Sir Martin has committed £40m of his own money to the new venture.

Sir Martin left WPP following an investigation into allegations relating to the use of company funds to pay for a sex worker - which he has vociferously denied.

His ability to establish a business in direct rivalry with WPP, the owner of J Walter Thompson, Ogilvy and Young & Rubicam, while retaining unvested share options led to a limited shareholder protest against the chairman, Roberto Quarta, at last month's annual general meeting.

Sir Martin remains a significant shareholder in WPP, with much of his wealth tied up in the stock of the company he took from a manufacturer of shopping baskets in 1985 to bestriding the global advertising industry.

By the time he stepped down in April, WPP was valued by the stock market at more than £16bn.

Its shares have slipped in recent months, however, amid investor anxiety about the impact of marketing budget cuts and shifts at major global advertisers.