Meeting the stars of Toby Young’s cautionary tale, our critic tries to make a good impression

So you’re the movie critic for The Times,” says Kirsten Dunst, sounding a tad too surprised for comfort. “Er, yes,” I chortle. “Cool,” she breezes. “Your job is sooo hard.”

There is an awkward pause while we digest this touching moment of A-list pity. “I can’t imagine what it must be like sitting in a room full of critics,” shudders the 26-year-old star. “I’m not into that kind of negative energy whatsoever.”

The sensible question to ask Miss Dunst at this painful juncture is “So what on earth are you doing here?” We are in a caravan on the film set of How to Lose Friends & Alienate People - a romantic comedy about an aspiring British critic who falls hopelessly in love with Dunst in New York. But there’s a thundering knock on the door and Simon Pegg noisily enters and plonks himself on the banquette next to her.

Pegg is the blundering star, and geeky alter ego of Toby Young, the maverick journalist who wrote the bestselling true story on which the film is based. Young’s brilliant account of his short and inglorious career working for the world’s most glamorous fashion bible, Vanity Fair, is a sublime exercise in public humiliation. But it’s also a pin-sharp portrait of the skin-deep loyalties and rampant egos to be found in abundance in the rarefied climes of high fashion, fabulous wealth, and untouchable celebrity.

Young was, quite simply, wildly out of his depth at Vanity Fair - socially, financially and emotionally. Given the shorts, socks and sandals that Pegg is sporting to play the part, he was also a sartorial disaster area. This is the first time I’ve met the actor and the brains behind those box-office comedy smashes Shaun of the Dead, and Hot Fuzz. What immediately strikes you about Pegg is the size of his head. It’s enormous, and almost perfectly round. The ginger hair has been cropped and dyed ash blond, and before I can control myself the $64 million question slips out. The costume begs the question. “Simon, you’re playing Toby Young. Is he a total arse?”

“Strange you should ask that,” Pegg says. “This is the first film I’ve ever done where most of the journalists who interview me will probably know Toby, and many will be sharpening an axe for him. But I met Toby after he’d changed into a better person, after his ‘alienating’ days at their height and he’s a joy.”

Having not met Young in the flesh, I’m not at all sure what Pegg means, but it sounds vaguely ominous. (Dunst has also met the excitable writer, who was especially keen to practise a scene with her. This, however, shouldn’t stretch anyone’s imagination in terms of what or why.)

What is undeniable is the uncanny pulling power the film has exerted over Hollywood. Danny Huston, Megan Fox, Jeff Bridges and Gillian Anderson queue up to bury knives in the hero’s back. “Graydon Carter (the real-life editor-in-chief of Vanity Fair) is more than happy that Jeff Bridges is playing him,” smiles Pegg.

The temptation to prick the glossy reputation of an institution such as Vanity Fair must feel almost subversive to stars in the league of Dunst. “Have you ever been photographed by Vanity Fair?” I innocently ask her. Pegg cannot believe his ears.

“The magazine?” checks Kirsten. “Yeaarh. I’ve been on the cover.” Obviously a lot of covers, if Simon’s face is anything to go by. One forgets that Dunst is Spiderman’s official squeeze, and the star of such esoteric wonders as Eternal Sunshine of the Spotless Mind and the rom-com Wimbledon. “I’m usually roped in for the young Hollywood ingénue covers they do … you know … ‘Here’s the bratpack.’”

Before Pegg can vent his disbelief at my celebrity cover ignorance, he is called back on set because of a rare and miraculous outbreak of sunshine. Robert Weide, the director, has been trying to shoot an exclusive garden party in the Hamptons for the past three weeks. It doesn’t help that we are exactly two miles from Box Hill and suffering the wettest month on record. But the soaking lawn in front of Headley Hall in Jane Austen country is suddenly, and briefly, transformed into a sunny corner of New England.

Behind the camera, lights and action, floats the familiar figure of the film producer Stephen Woolley, wearing his trademark rose-tinted shades and Deep Purple hairstyle. This is one of the biggest gambles of his career. Was his head turned by the success of the book, which was a No1 bestseller here and in the States?

“What struck me about the book,” says Woolley “is that it’s rooted in The Modern Review, the magazine Young edited in 1991-95 to such brilliant effect. The mag championed the likes of Tracey Emin, Nick Hornby, Will Self and Julie Burchill. It raised lowbrow material into highbrow art. It challenged French film gods such as Chabrol and Goddard and asked ‘What’s wrong with Arnie?’ It’s about the perils of taking ourselves far too seriously. And that indeed is the point of the film.

“The first thing I did, of course, was fire Toby. His treatment was awful and he had no idea how to adapt a book. I said ‘Look. Here’s the money. Just go away.’ Which he didn’t take too kindly to, given that we had just persuaded him that we were the perfect producers for his baby.”

Peter Staughan’s new script treatment, says Woolley, has given Young’s comedy a romantic spine, an American heroine (Dunst), and infinitely more movie logic.

“Our inspiration has always been Billy Wilder’s 1960 movie The Apartment, with Jack Lemmon forever trying to climb up the greasy corporate pole,” Woolley admits. “That’s what happens to Toby’s character. The higher he gets, the lower he gets. Toby went to Vanity Fair thinking ‘That’s it. I’ve made it.’ Only to discover that he hadn’t been hired for who he was, but for his novelty value.”

Young’s set visits have apparently been legendary. “In true Toby fashion he did not enamour himself to us all,” says Woolley with wonderful tact. “I love Toby. He’s a good guy. He’s a genuine larger-than-life character, and he’s got honesty and balls. But he’s also got some form of Tourette’s syndrome where he says the wrong thing at the wrong time. If the phrase, ‘He is his own worst enemy’ was coined for anyone, it is Toby.”

How to Lose Friends and Alienate People is released on Oct 3