Profile: Enter genius, from left; Patrick Marber

Once a writer of cruel satire, he's now set to become the top dramatist of his day.

THE future of British theatre has just walked through the door of the Savoy and no one seems to have noticed. Patrick Marber slopes up to me in the foyer, a shy smile in his eyes. There is no Pinterian gravitas about him, no booming voice and opinions. Nor is there the Stoppard swagger; no silk scarf flung jauntily about the neck or the confidence that comes from having wooed Felicity Kendall. Marber is a shadows man, a writer and director who practises his art away from the spotlight.

But the author and director of the huge hits Dealer's Choice and Closer - the latter just voted Best Play of 1997 at the Olivier Awards - is in the spotlight now, and he is making a good impression. He is impeccably dressed in a suit that wants to be Comme des Garcons, and no doubt soon will be. His thick, dark hair is anointed with expensive smelling unguents. He is good-looking in an unobvious way, with generous lips and piercing blue eyes.

While I can't claim to be suffering the same anticipatory tremors apparently experienced by every female interviewer who had a chat with Jack Nicholson on his recent round of publicity, I must admit to being a little nervous before my meeting with this latest young turk of theatreland. Within the business he has a reputation for being (variously) rude, a genius, demanding, talented, difficult. I must report, however, that Marber is one of the most reasonable and sane playwrights you could wish to meet. He has a disarmingly bashful manner, insisting that he is "fat and old" (he is 34, for goodness' sake) and "jowly and overweight". It seems a defence - as if he's trying to get there before someone else says it.

He grew up in Wimbledon (his father was, still is, a voluble financial analyst in the City), where he was conscious that life wasn't quite as exciting as it might have been in trendier north London. "I wanted to come from Camden or Islington," he has said. A Jewish boy who was sent to a Catholic school, he had a rich fantasy life in childhood, in which most of his dreams were centred on sport. He once crept under the gates of the nearby All England Tennis Club and ran around on an empty Centre Court. He didn't discover books until adolescence.

Marber went on to spend gambling- and alcohol-soaked nights at Oxford, experiences which he put to good use in Dealer's Choice. Before that, however, he cut his teeth in stand-up comedy. A member of the now legendary On The Hour radio team, put together by Armando Ianucci, Marber also worked with Chris Morris, Steve Coogan on radio and television before splitting to work with Coogan on the phenomenally successful Alan Partridge series. Marber was one of the creators of Partridge, and the incisive if heartbreaking truth of that parody foreshadowed much of the dramatic verve that he would later unleash in Closer, a searing exploration of love and sex among a group of four young Londoners.

Theatre likes its prodigies to train either as actors or as serious students of the profession, building slowly to a great London debut. But Marber broke the rules. And he is now quietly carving out a career for himself as the writer who may be the greatest dramatist of his generation. Closer this week transfers to the Lyric Theatre, Shaftesbury Avenue, after a sell-out run at both the Cottesloe and the vast Lyttleton theatres at the National. As a director - and to combine writing and directing as Marber has done is remarkable in itself - he is about to take on David Mamet's new play The Old Neighbourhood at the Royal Court.

Marber's early days in stand-up taught him the basis of his own dramatic style. "There's no point setting up a joke for five minutes and then delivering a punchline because the audience will be at the bar," he says. "My dialogue probably reveals the paranoia of the stand-up: if you're not quick and interesting they will be gone." He has said with characteristic candour that "great comedy is always sadistic" a comment that could have been the creed of such programmes as The Day Today and Knowing Me Knowing You.

Now being in the vanguard of playwriting, Patrick is often called upon to put his name to petitions about the state of the arts. He demonstrates an unwavering reasonableness and balanced set of views. He has signed up to the Independent on Sunday's campaign to help funding of the arts. "A part of me would like to see the money go to hospitals or housing, but I have benefited so greatly from funding for the National Theatre, which has been incredible. I know it's hip to slag off theatre, but I just do not buy that." His voice becomes more animated and angry. "Okay, it is the case that theatre is expensive in this country but when you work in theatre you understand why that is. It is one of the things that we do so well. Anyway you can see Closer for under a tenner, and I happen to think it is worth it."

For a quiet, middle-class boy whose only sense of civic pride as a child came from the Wombles, Patrick has deeply-felt political opinions. Ken Livingstone is a hero to him. "The GLC period was a wonderful time to be living in London," he says. "There was great excitement. I hope he becomes Mayor. The thought of Jeffrey Archer becoming Mayor is an appalling prospect."

Marber says he likes Clare Short and that Peter Mandelson is being unfairly maligned - "I think he has worked his bollocks off for his party". But when I ask him about the Millennium Dome, the question brings a snort of revulsion. "I am very anti-Dome. There is terrible poverty in this country. We don't need a Dome; we've got far better things to spend our money on."

Closer started out as quite a political play, but in the end Marber took the politics out of it, a process which eventually reduced its length by half. He describes this painful editing process as "a gradual recognition of the play I was writing". The final piece retains the essence of one aspect of politics - sexual politics. As Marber says: "It's about power and how people operate with the gloves off". Closer has been compared to David Hare's Skylight, Harold Pinter's Betrayal and Mamet's Sexual Perversity in Chicago.

He is modestly flattered by the comparison. ("No, but they are writers of great genius") but refutes the specific reference. "I dispute that Closer is about betrayal. Betrayal is one of the elements. I direct my actors to love each other. I think of it as a drama of love and sex rather than a drama of deception and manipulation, or hatred".

There is a jug of milk on the table from one of Patrick's innumerable coffees, and I ask him whether he thinks it is half full or half empty. Quick as a flash he replies: "It is sour." And then he pauses, his faces cracks into a smile and he admits: "I wrote that line for my stand-up." The comedian has come a long way since he toured the smaller clubs in the Eighties with his contemporaries Jo Brand and Jack Dee, and he has achieved a lot.

The moroseness which has been apparent in the past seems to be entirely absent now. This clearly has much to do with his girlfriend Debra Gillett, whom he met while he was directing a production of Dennis Potter's Blue Remembered Hills. The pair have been together for two years, and when he collected his award for Best Play at the Oliviers he rather touchingly dedicated it to her. "She's so funny," he says. "She makes me laugh all the time."

'Closer' opens on 31 March at the Lyric Theatre, London W1, previewing from Thursday. Box office: 0171 494 5045.