Stewart hits out at Ford

The 65-year-old admitted to feeling "total shock" at the Blue Oval's decision, announced in September, to pull the plug on both the Jaguar team and Cosworth Racing at the end of the 2004 season.

"One of the great things about Ford is that the company was a global thinker," said Stewart. "I believe not having a presence in Formula 1 will have long-term implications for the company. Even if it is not the case in America, grand prix racing still draws the biggest [global] TV audience."

Stewart's ambassadorial role for Ford dates back to 1964, when as a young driver he was handed a contract to promote the company's products in Britain. Each of his three world championships came in Ford-powered cars, and more recently in the late 1990s he persuaded the Detroit behemoth to fund his own F1 team, Stewart Grand Prix, which it took over in 1999 and rebranded as Jaguar Racing.

The Scot stayed on as a consultant, but the relationship became somewhat strained last summer when it became clear that he was planning to work with the Royal Bank of Scotland, which is expected to announce a sponsorship deal with the Williams team shortly.