Casually attired in faded blue jeans and a long-sleeved green T-shirt that he has somehow managed to singe, Simon Cowell takes a sip of tea and a mouthful of cake, lights a menthol cigarette with an over-sized match from the posh perfumer Jo Malone and settles back on the sofa. His ex-girlfriend Sinitta, the 1980s pop star, whom he helped to make famous and who now works for him, flutters around, half personal assistant, half nursemaid.
Cowell is full of contradictions. Though his public profile is "Mr Nasty", he knows how to turn on the charm. He is also a man who has profited hugely from the business of creating instant celebrity, while working long and hard to attain his own.
Already a successful music talent-spotter when he first came to the public's attention as a judge on the first series of Pop Idol in 2001, Cowell has branched out into television production through his company Syco TV, and he is now worth a reported £35m. He was recently quoted as saying that he would like to be worth £100m "in a few years".
Following a three week winter break in Mauritius with a dozen family and friends including girlfriend Terri Seymour and mum Julie (Cowell, who is often lampooned for wearing high-waisted trousers, was mocked by Heat magazine for his high-waisted swimming trunks on the beach), the 46-year-old will spend the early part of this year at his second home in Los Angeles, where he is filming the fifth series of American Idol.
The US version of Pop Idol, which starts tomorrow on Rupert Murdoch's Fox TV network, is the most-watched show on American television, with ratings averaging more than 27 million. It is also the most expensive programme for advertisers after gridiron's Superbowl, with a 30-second spot costing more than $700,000.
As a consequence, Cowell is a household name in the US, although he shies away from the word "celebrity". "I just consider myself to be quite well known in America now," he says with deliberate modesty.
Back in the UK, ITV has signed up for a further two series of The X Factor, the show made by Syco, which pits three categories of singing hopefuls against one another - 16- to 24-year-olds, over 25s and groups. The second series, which concluded just before Christmas, performed the rare feat of achieving higher ratings than the first - 9.2 million viewers watched Mancunian shop assistant Shayne Ward win the contest, more than a million up on the previous year's final night.
The X Factor's appeal is a combination of the awfulness of the hopefuls who turn up for the early auditions, the promise of overnight fame for the more talented contestants, and the strong personalities of the three judges - Sharon Osbourne, Louis Walsh and Cowell.
For Syco, the 18-week series is a huge money-spinner, with additional funds coming from the winning artist's record sales, plus a share of the telephone and text voting by viewers.
Despite the growing success of The X Factor, Cowell is not ready to rest on his laurels. He will use his time in Los Angeles, where Syco is opening an office, to work on improving the show.
"We sat down in Los Angeles in February, went back over the first series and agreed that we could make 35 to 40 per cent of the show better. I will do the same again in February this year. I don't like getting complacent and I always put myself there as a viewer, not as a producer," he says.
Whereas some television producers might be tempted to quit the UK for the more lucrative American market permanently, Cowell thrives off the different energies of Britain and the US. "I am very lucky. I can work in LA and London. After three to four months, I am itching to get back to London, but come the end of January, I'm looking forward to going out to LA. One makes you appreciate the other."
While money is important to Cowell, it is not his only god. He clearly derives just as much satisfaction from the process of producing a hit show. "There is a much bigger prize to be won in America than the UK in terms of revenues. You can make a lot more money over there, both as a format owner and on screen. But I think the UK is one of the hardest markets to crack. I like launching shows in the UK and sorting out the problems before you go to America."
With so much at stake, it is inevitable that rows will sometimes break out in tellyland. Cowell recently found himself at the centre of a dispute with the Pop Idol creator Simon Fuller, who sued for breach of copyright, claiming that The X Factor was a rip-off of his show, an assertion Cowell dismissed as "utterly ridiculous". To complicate matters, American Idol was in the process of renegotiating its contract with Fox. If Cowell had decided not to appear on it as a result of the lawsuit, the US network might have decided to drop the show altogether in favour of an American version of The X Factor.
A £100m high court battle was averted when Fox brought about a settlement. The network signed up American Idol for at least four more series, with an option for six, while (for an enhanced fee) Cowell will remain a judge on the show for at least five series. In return, Fuller will take a share of The X Factor.
"I got a good deal, but everyone came out of this very well. I don't think anyone was unhappy with what they got out of it," says Cowell. "More importantly, it brought a bit of peace and harmony, which we haven't had for a couple of years. I would say, honestly, that Simon and I came out of this better friends at the end than we were when we went into it together." Even after the writ was issued, he insists, the two Simons continued to meet and have dinner together.
Taking The X Factor to America is "not on the radar at the moment", but Cowell does not rule it out altogether. "It's certainly not impossible, but this time everyone will have an input. It won't be my decision or Fox's. It will be a joint decision."
Show business is a serious matter for Cowell, whose attention to detail is matched only by his emotional involvement. This is why he insisted on changing the second series of The X Factor, making the auditions less "dark and dingy", introducing a more "concert like" stage and relegating the judges to a less prominent role - a series of minor alterations adding up to overall success. It is also why he was initially upset when he was given the groups to coach in series two, believing, correctly as it turned out, that they had less chance of winning. He quickly reconciled himself to the task. "I like being the underdog. It makes you try harder," he says.
The "Mr Nasty" tag is one that Cowell hopes he has managed to shrug off. "When we first did Pop Idol, it was a different type of show. I think myself and Pete [Waterman, a fellow judge] probably came over as being a bit coarse and unpleasant. The more people have watched these shows, the more they understand that it's based on honesty, not on trying to be an arsehole."
Since the early days of Pop Idol, Cowell has remained loyal to ITV, with whom he has a golden handcuffs deal. ITV recently announced that it had signed up for another two series of The X Factor. But the broadcaster no longer has a first-look agreement with Syco for other shows in development.
"There was no reason to work with another channel, because ITV was very enthusiastic about the shows we wanted to make," Cowell says. "I certainly believe I have to repay their faith in me, because they took a chance years ago by giving us a break with Pop Idol and The X Factor."
But he adds: "I got to the stage where I felt that we couldn't just be making ITV shows and we had to be free to go to whatever broadcaster we felt appropriate. That changed with this new deal.
"We would work with anyone, whatever we think is the best home for one of our shows - Channel 4, BBC, Five, Sky, any of them."
In the past, Cowell has been scathing about the BBC, but his views have changed following the appointment of the former Talkback Thames chief Peter Fincham as controller of BBC1.
"There's been a huge change recently at the BBC. I know Peter very well and like him a lot. He's commercially minded, so I think he and I would get on very well." He still harbours some doubts, however. "I think you have more freedom with ITV than with the BBC. I'm not sure the BBC would give us the creative freedom we have had."
Cowell will not be drawn on recent changes in the top management at ITV, even though the two people he worked most closely with - the entertainment chief Claudia Rosencrantz and the programme director Nigel Pickard - have both quit following the appointment of Simon Shaps as director of television.
He describes Shaps as "a bright guy", adding: "I don't think there'll be too many changes over there. I tend not to get too involved, because it's not really my business who runs the network. Our focus is just on the type of shows we want to make."
As someone competing for ITV commissions from the outside, he does not think "for one moment" that the in-house production company Granada has an unfair advantage. "If you've got a really good idea, politics will never get in the way."
It was timing rather than politics that got in the way of one of his forthcoming projects for ITV, the celebrity singing contest Star Duets, which bears an unfortunate resemblance to a musical spin-off of Strictly Come Dancing unveiled a few days earlier by the BBC. The blow was softened, however, when Fox bought the format in the US.
"I know for a fact that we came up with our idea first," Cowell says. "ITV were a bit slow to commission it. I think we've probably lost the battle in the UK, but we may win it in America."
Syco is also working on a couple of films, one a big-budget Hollywood movie and the other a low-budget Irish film, both fictional accounts of the music industry. And Cowell is hatching plans to expand into the internet, an area he admits he is only just beginning to understand.
After leaving school at 16, Cowell worked as a runner at Elstree Studios, close to where he grew up, where his duties included making the tea and performing menial errands. His first foray into the record industry was in the post room at EMI Music Publishing. It was not long, however, before he had worked his way up to become a record producer and then to set up his own label, Fanfare Records.
Sinitta provided his first big break. He had so much confidence in her song "So Macho" that he invested £5,000 in making a record and video, which he had to release three times before it became a hit. The single went on to sell a million copies, on the back of which he was recruited by BMG Sony as an A&R (artist and repertoire) executive.
At Sony, where he remained for 15 years, he was responsible for signing acts such as Curiosity Killed the Cat, Sonia and Robson & Jerome. But success was tempered by a difficult period in his early thirties, when he went bankrupt and was forced to move home temporarily.
"I started a label and probably did what every other A&R guy goes through. You start to believe your own hype, surround yourself with people who will just nod at everything you say, go through a sticky patch where you start blaming the world, then you realise that, actually, it's you that got yourself into this situation."
Syco, which has a staff of just eight people, still works within the BMG Sony building looking after artists such as the Irish boy-band Westlife and Il Divo, the male quartet who have enjoyed No 1 hits in 13 countries.
Cowell is keen that the recording and television sides of the business work together. "I try to blend everything. I don't like a them-and-us attitude. It's manageable because it's such a small staff. Our intention is always to look at everything as a worldwide brand and protect that brand, whether it's an artist or a television format."
Other forthcoming projects include The American Inventor, a new series which Cowell has devised with British entrepreneur Peter Jones to recognise inventing talent, launching on ABC in March and Paul O'Grady's Got Talent, an old-fashioned variety act contest, which Syco is making for ITV, despite O'Grady's recent defection to Channel 4. Later this year, Syco is launching a new classical quartet in the style of Il Divo, this time with two male and two female singers.
It does not concern Cowell that, although many of his artists enjoy commercial success, few have earned critical acclaim. "When you do this job, the one thing you can't do is guess what other people would like. You have to do things based on what you like. Luckily, I have incredibly juvenile taste at times and I also have very populist tastes.
"I've never been ashamed of popular culture. If you walk into a French restaurant and you want to order fish fingers and chips, good luck to you. I don't like cultural snobbery, and record companies are a hotbed of cultural snobs." By choice, Cowell would listen to Frank Sinatra and watch Top Gear (a car enthusiast, he owns a Range Rover, a Rolls-Royce and a Porsche).
He warms to his theme. "I'm not making shows or records to be critically acclaimed. I want as many people as possible to buy my records and watch my TV shows. That is a buzz.
"I cannot bear snobbery. I'm beginning to loathe the upper class in this country. I don't know whether I am becoming a socialist or not, but I just find the idea of treating somebody differently because they're born in a different way to you absolutely ludicrous."
After five years in the limelight, what is it that keeps him going? "I enjoy working. When people ask me what my hobbies are, I say that I don't have a hobby, because work is my hobby."
He believes he has his parents to thank for his work ethic. "They taught me and my brother from a very early age that you have to earn everything you get. We were encouraged from the age of 10 to take holiday jobs and weekend jobs to earn our own pocket money.
"I didn't have A&R Idol when I was starting off. I had to start at the bottom and climb very slowly to whatever you perceive to be the top. I'm glad I did it that way. I wouldn't have wanted any quick breaks."
When he looks back on his career in 20 years' time, what would he like to have achieved? "That's a very good question. I don't believe in leaving a legacy. I'm sure I won't. I hope I can look back and say that I've had a great time."
And with that, his very own personal organiser, the former pop star Sinitta, reappears to hurry him on to the next appointment in his busy agenda.