The account this week appeared to be heading for Grey after a last-ditch effort by Sorrell to accommodate Seat within WPP, whose biggest single client is Ford.
Grey has put huge effort into winning the business. Ed Meyer, the Grey chairman, is understood to have offered executives of the Spanish carmaker very generous terms in order to secure it.
The fate of the account had been problematic ever since Cordiant, the parent company of Seat's agency network, Bates, was taken over by WPP in a £266 million deal in July.
The takeover meant Seat would have to share WPP not only with Ford's Jaguar, Volvo, Range Rover and Mazda brands but the Fiat-owned Alfa Romeo, which is handled by WPP's Red Cell operation.
WPP is understood to have proposed setting up an office in Barcelona under the Bates name specifically to handle the business but this offer appears to have been refused.
Grey declined to comment on the impending appointment but the network is well equipped to take the account. It has no auto business and has an existing relationship with Seat's Volkswagen owner through its media independent, MediaCom.
The account switch has raised speculation that Grey will attempt to retain continuity on the account by taking on some of the 30-plus Bates staff currently running the Seat account out of Barcelona. Seat failed to return calls as Campaign went to press.