Months of wrangling, rows and manoeuverings ended on Wednesday, when Cordiant shareholders voted overwhelmingly in favour of WPP's £266 million offer.
Sorrell told Campaign: "We are very pleased with the outcome and think that the shareholders have acted in a very responsible manner."
One of the first client casualties of the deal could be Seat, the Spanish motor group, whose pan-European advertising account is held by Cordiant's Bates network.
Ford, WPP's largest single client, is said to be imposing tough conditions on sharing the group with another car manufacturer. If WPP cannot meet them, Seat will have to be cut loose, with Grey Worldwide the favourite to pick up the business.
Speculation about the destination of the Seat business was further fuelled when it emerged that Ed Meyer, the Grey chairman, flew to Barcelona two weeks ago to meet Seat chiefs.
Seat said this week that it was reserving its position. "We're happy with the people and the service we're getting," a spokeswoman said. "We'll have to wait and see how things turn out." Ford was unavailable for comment.
An industry source said: "Sorrell is doing all he can to hang on to Seat, which certainly doesn't want to leave."
Meanwhile, there is festering dispute between Sorrell and his Publicis Groupe counterpart, Maurice Levy, over the sale of the 25 per cent stake that Cordiant holds in ZenithOptimedia.
Publicis, which owns 75 per cent of the media buying operation, has an option to buy the rest for £75 million. Now Sorrell is said to want a further £10 million, claiming Levy broke an agreement with him not to bid for Cordiant.
Levy argues that Cordiant's board double-crossed him when it changed its mind at the last minute not to accept his offer.
In the meantime, WPP is beginning the process of dismembering Cordiant after 99 per cent of its shareholders backed Sorrell's bid.
They included Active Value, the rebel shareholder group that held a 28.75 per cent stake in Cordiant in an attempt to derail WPP's bid, and Nahed Ojjeh, the wealthy Syrian chess promoter, who had almost 11 per cent.
However, Active Value insisted the fight wasn't over by announcing that it was well advanced in bringing legal action against certain individuals to recover losses shareholders had suffered.
The move reflects outrage at payments made to David Hearn, Cordiant's chief executive, who will walk away with more than £1.5 million, and Andy Boland, the finance director, who will receive more than £580,000.