Christopher Hampton: The award for least prepared speech goes to...

The 'Atonement' screenwriter is up for his second Academy Award tonight. If he wins, he must remember his lines – or face his family's wrath

'I do find occasions like the Oscars nerve-racking... in case you win. You've got to get up and say something' (Jonathan Evans)

The first time Christopher Hampton won an Oscar, he made a terrible mistake. "I forgot to thank my wife and children," he says, "which they have never forgotten." They've had plenty of time to stew: the British writer was given an Academy Award for his screen adaptation of the play Dangerous Liaisons in 1989. Shocked by the win, he had no speech ready – but suddenly found himself at the microphone with a golden statuette in his trembling hands and time running out fast. "There was a man in white gloves standing no further away from me than the end of this room, drawing his finger across his throat to signify, 'Kindly get off.' So I did."

So passed – all too quickly – the greatest moment in a screenwriter's life. Winning once is extraordinary, but tonight Hampton may get to have another go when the 2008 Oscars ceremony takes place at the Kodak Theatre in Hollywood. This time he has been nominated for his screenplay of the Ian McEwan novel Atonement. The film stars Keira Knightley, and has a chance of four honours, including Best Picture.

There is a very strong chance that Hampton, a boyish 62-year-old with long, grey-blond hair and a vaguely New Romantic dress sense, will join the élite club of double Oscar winners that includes Marlon Brando and Tom Hanks (and his fellow Brit Julie Christie, if she also wins tonight). So does the wordsmith plan to write a speech this time? "No I don't. I sort of think vaguely about what I might say. I don't think I'll win." He smiles. "I didn't think I was going to win last time either, but this is a very good year for films. There's the Coen brothers and Paul Thomas Anderson and Ronnie Harwood and ... what's the other one?"

Sarah Polley for Away From Her, the film starring Christie, actually. It's about Alzheimer's. Hang on, was that a screenwriter's joke he just made? The others are up for No Country for Old Men, There Will Be Blood, and The Diving Bell and the Butterfly respectively. "There is a feeling that the Coen Brothers have waited a long time," he says, "but this is their year. It's their turn."

We meet the day before he leaves for LA, on the top floor of a gorgeous townhouse near Notting Hill Gate. The view is spectacular, over the rooftops or down through the frosted bones of trees to Ladbroke Square Gardens. Hampton writes here with his back to the window, with a pen on lined paper. There are several new pages on his crowded desk; but for now he is padding in with coffee, dressed all in black with an untucked shirt and looking like David Bowie's epicurean brother.

"I won't horrify you by saying how much I bought this place for," he says with a satisfied chuckle, "but it was 1971. Notting Hill was different." He sanded the floors himself. "I am the world's worst DIY person, but I got a ... what would you call it?" Sander? "Hmm. Cut through the power cable. I never did finish it. Under the rug, there is still a patch of grime from 1971."

He had a lot else to think about at the time. Hampton was already a star, the youngest playwright ever to have his work performed in the West End.

Born in the Azores, the son of an engineer with Cable and Wireless, the bookish boy had lived in Aden, Alexandria, Hong Kong and Zanzibar as well as Lancing College in Sussex, where he became friends with his fellow playwright David Hare.

It was Hampton who found success first. His debut, When Did You Last See My Mother?, transferred from an Oxford University production to the Royal Court Theatre and on to the big time. It was followed by Total Eclipse, about the poets Rimbaud and Verlaine, and The Philanthropist, which was a big hit. All this had happened and yet he was still only 25 when he moved into the London flat. His first-class degree in French and German at Oxford was still new, and he was in love with Laura d'Holesch, a nurse who had been his landlady. They have been married for 37 years. One daughter, Alice, is studying natural medicine in Australia; the other, Mary, is a folk singer whose first album is by the CD player, next to one by Django Reinhardt.

The flat is now an office. He lives nearby, but commutes across the Atlantic. The irony is that Hampton may not have been in with a chance of winning a second Oscar if a bumptious young replacement director had not told him to junk everything – after 18 months of hard work – and start again. "I had a moment of despair," he admits. "I thought, 'Oh God!'"

Hampton had wanted to adapt Atonement ever since he first picked up a copy at an airport. "It had all those cinematic elements, of the hot days in the country house, Dunkirk and the hospital." The novel Atonement tells the story of a terrible misunderstanding leading to unjust imprisonment and thwarted love. It jumps from the English countryside of the 1930s to the evacuation from France in 1940, wartime London and the present day – dazzling in prose but extremely difficult to film. Making a brilliant book into a brilliant script may sound simple, but his Oscar nomination is recognition that in this case it was a fiendishly difficult technical challenge.

Hampton worked closely with McEwan and the director Sir Richard Eyre, but then Eyre quit. "He decided he would go for a sure thing, which was Notes on a Scandal. And there we are." (Notes grossed half as much as Atonement.)

Eyre's replacement was Joe Wright, a 35-year-old whose first major film, Sense and Sensibility, was nominated for four Oscars. "Joe, who I had never met before, said: 'The script is fine and dandy but I would like you to start from scratch.'"

But this was Christopher Hampton: Oscar winner, translator of Chekhov, Ibsen and Yasmina Reza's hit play Art, author of scripts including The Honorary Consul and The Quiet American and director of Carrington. With a CV like that you don't get told to start again, surely? "I did."

If it offended him, he doesn't say so. Hampton has elegant manners... and anyway, he was won over by Wright. "It was clear to me after the first couple of conversations that he knew what he was doing. Joe said he would prefer to return it to four sections like the book, reserve the final surprise and get rid of all voiceover. That was tempting."

The two men went to a house in Florence for a fortnight to work through the script, line by line. "We negotiated. He would write scenes and I would say, 'Oh no, no, no... but I see what you mean.' A writer always knows it is the director's film."

Back in his twenties, fearful that success might be shortlived, he had decided to try for a long career across a wide range of genres. "Success brings pressure," he says, "but it is always followed by resounding failure." His biggest hits have come with translations and adaptations.

His friend David Hare has suggested this is a waste of talent, but Hampton doesn't see it like that. He quotes his favourite novelist, Flaubert, saying that in great writing the author's personality should be absent. "It is a sort of self-concealment." That makes it hard to pin down the Christopher Hampton style. "I know. But it's fine, because each piece probably has its own appropriate style." He is equally enigmatic about his private life, choosing to smile and say little in response to questions about Laura. But he does quote Flaubert again. "He said: 'Put all your rage and madness into your work and live as orderly a life as possible."

A critic once said Hampton had lived his life in reverse: spectacular early success followed by "umpteen abortive projects". Two-thirds of the films he has written have not been made – but 13 have, so far, and one in three is a higher hit rate than most. Asked how it works, he describes the frustrations of trying to adapt Tulip Fever, by Deborah Moggach. "I sent drafts. Eventually I went to Los Angeles. [The producers] were involved in an extremely important movie – I think Lara Croft II or something – therefore were pretty unavailable. Eventually we did have a meeting which lasted for 40 minutes, over steak sandwiches, so you couldn't always hear what people were saying. That was that. I was sent back to England." He redrafted but refused to remove "the best scene in the film" in which a servant eats an all-important tulip bulb, thinking it is an onion. "Next I heard, they had hired Tom Stoppard."

Hampton is not short of work: after our chat he must go to rehearsals for his translation of Yasmina Reza's play The God of Carnage, then come back to the flat to work with two actors from Stephen Frears' forthcoming film of a Colette novel. Two of his own plays are also to be filmed, one by David Cronenberg. "Then there's this jollification in LA to punctuate it all."

So, how will the hours leading up to the Oscar ceremony be spent? "Partying. There's lunch parties and brunch parties and dinner parties and party parties. I'm not much for all that, but it's nice once in a while. The offers have certainly begun to arrive, in a way they conspicuously didn't a couple of years ago."

Tonight's show was nearly off, of course, when the Hollywood writers went on strike. Hampton supported them. "I wish our guild here was as militant. There are lots of health benefits and retirement stuff they do for their members which we haven't yet got together."

The Writers Guild of America, of which he is a member, reduced the Golden Globes to a press conference. "I actually secretly enjoyed it. We [the Atonement team] all gathered in a big suite at the Chateau Marmont [the castle-like hotel that towers over Sunset Boulevard] and watched them open the envelope on television. It was all rather jolly. I do find occasions like the Oscars pretty nerve-racking... in case you win. You've got to get up and say something."

No long speech if he wins tonight then, but two long-overdue words for Laura, Mary and Alice, expressing gratitude at last for their support through the flops as well as the hits. When the name of the winner is announced, listen out for an atonement.

Filmography

A Doll's House (1973) Script based on Henrik Ibsen play

Tales from the Vienna Woods (1979) Adapts play by Odon von Horvath

The Honorary Consul (1984) Graham Greene adaptation

The Good Father (1985) Adapts custody-fight novel

The Wolf at the Door (1986) Life of artist Paul Gauguin

Dangerous Liaisons (1988) Adapts own play, from 18th century French work

Carrington (1995) Own life of British artist

Total Eclipse (1995) Own play about Arthur Rimbaud

Mary Reilly (1995) Based on Valerie Martin novel

The Secret Agent (1996) From Joseph Conrad novel

The Quiet American (2002) Does Greene with Michael Caine again

Imagining Argentina (2003)

Adapts oppression novel

Atonement (2007) Screenplay of Ian McEwan novel. Stars Keira Knightley and Ailidh Mackay. Up for four Oscars tonight.