After the shooting of American Idol, Simon Cowell retreats to a car-park trailer, where it seems all the real business of America’s most popular television show is done, amid cigarette smoke, on or around the trailer’s patterned brown chairs. This evening Cowell is thick in discussions with Simon Fuller, the owner of the Idol format, who once tried to sue Cowell for copying the idea for The X Factor, Cowell’s UK talent show.

The two are now allies, or at least business partners. “We’re both incredibly competitive,” Cowell says, “and when we work together, it works incredibly well – even if we’ve fallen out the other 5 per cent of the time – and, anyway, I see some money from the record deals.”

Idol winners are signed up to Fuller’s 19 label, which works with Cowell and Sony, their record company partner, allowing both men to generate even more income subsequently.

American Idol, watched by more than 27 million people every show, is probably the largest property in US network television today, generating, some say, as much as $900 million (£620 million) of advertising revenues annually. Fox, the show’s broadcaster – owned by News Corporation, parent company of The Times – keeps the exact figure to itself.

Eight series in, and Idol is a gold-mine for everybody involved, most of whom, it turns out. are British or European. It is the principal source of Fuller’s $75 million profit in 2008, despite the work that the Svengali does for David Beckham. According to Nigel Lythgoe, until recently one of the show’s producers, Cowell earned $36 million last year direct from Idol, a figure that nobody has strained to deny. It should be more this year, as he signs one-year contracts, giving him the chance to extract more cash annually.

The real legwork is done not by Simon Fuller’s 19 Entertainment, but by FremantleMedia, the London-based production company owned by RTL, the European media group. The key producers of the show are Ken Warwick and Charles Boyd, both of whom are British, reporting to their French boss, Cecile Frot-Coutaz. The only important American in the mix is Mike Darnell, the pint-sized, leather-jacket wearing commissioner of “alternative programming” for Fox, who once cheerfully predicted all the Brits would be “back home in six weeks”.

In person, Cowell is, not surprisingly, supremely self-confident, but with none of his on-screen aggression. Selling pop to teenagers with the help of television is about the only part of the music industry that has grown in the past decade; he is unapologetic about his contribution to popular culture.

“I’d like to see what my critics have done to give people a shot at becoming pop stars,” he begins. Asked who else in the music business he admires, he singles out Bob Cavallo, president of Hollywood Records, whose artists include the teen favourites Hannah Montana and the Jonas Brothers.

Yet, for all the money (he also earns an estimated £7 million a year from ITV for The X Factor), Cowell complains that “something has to give”. If he wants to expand, he has to spend less time on television, or at least on screen. Idol takes up the spring in Los Angeles; in May, he returns to the UK for Britain’s Got Talent (Cowell’s other format) and The X Factor, on which works runs from June to Christmas.

Cowell still sees himself as working “on television, and running a record label”, but complains that after a day of filming X Factorauditions, he has to “stay up late and sign off on the Il Divo album” (the latest project involving the operatic cross-over group he created), all of which is taking a personal toll.

So, perhaps with a negotiation with ITV in mind, he hints that he might give up judging on The X Factor, as he talks up the potential of Cheryl Cole, his fellow judge. “My hope is that she can carry the show in the future,” he says. That would free up time for Cowell to try to earn more money on both sides of the pond.

Times Recommends

• Minister in talks with Saudis to protect creditors
• Premier Inn hits back in £29-a-room row
• Bankers hit back at 'populist' bonus supertax