Prada's cool. Gucci is posh. Versace shows you're rich. But if you want pure fashion with an intelligent streak, then this year's British Fashion Award winner is the designer for you. Who's that boy? Hussein Chalayan

Hussein Chalayan first came to the fashion world's attention when he buried his degree collection in a friend's back garden to discover how it would decompose. Now the avant-garde designer is finally being taken seriously. Last night, at a ceremony held at London's Natural History Museum, he won the prestigious British Designer of the Year award. He has previously been nominated three times. So why did it take him so long to win?

"Perhaps it is because the British have always been slightly suspicious of conceptual, so-called intellectual fashion," he says, "or perhaps it's because my clothes aren't sexy or sensationalist."

Or perhaps because it has taken him a long time to shake off his potty professor image. Not for him the histrionics or high camp posturing normally associated with the breed. He thinks carefully about each question before he answers it in much the same way as he agonises - and I mean agonises - over each and every garment before he offers it up to outside scrutiny.

In appearance, too, he is hardly a walking advertisement for high fashion. When I interviewed him he was, as always, dressed in low-key jeans, sweatshirt and clompy boots that have clearly seen better days, as has his closely shaved round head (much of his hair has dropped out - presumably from stress).

"This is an all-encompassing job," he says, explaining his frayed physical appearance. "It's mental, emotional, even neurological." He looks completely sapped of energy, lying back on a sofa, practically motionless apart from his knee, which jerks as if he's got a trapped nerve. "It's like a nervous twitch. I've had to train it to stop jerking, especially in important meetings."

Chalayan's reputation for obscurity started when he became the first designer in London to turn his catwalk shows into performance art. His performances featured dresses suspended by helium balloons, and razor- sharp suits that lit up with flight-path patterns. He produced dresses made from unrippable paper that could be folded into their own envelopes and sent through the post. In one show he encased his models' heads and faces with huge cones of polished wood. His "set" is a bare white cube, distorted by mirrors or walls that create dramatic perspectives, and featuring a live Gregorian choir. His latest invention is an electronically articulated plastic dress that spreads its wings as if coming in to land.

Chalayan has always been preoccupied with technology; at college he was always armed with textbooks on aerodynamics, philosophy and medicine rather than the latest issue of Vogue.

It wasn't so much the challenging nature of his work that posed problems, but rather his apparent lack of business nous, coupled with his perceived indifference to making wearable clothes. Prospective buyers were dazzled and baffled. But alongside his innovative "show pieces" he has never failed to produce clothes that have been cleaned of gimmicks.

Beneath the intellectual conceit of their presentation, the clothes themselves are simple and easy to wear. A jacket may defy the laws of pattern-cutting in its complexity, but the line is always pure.

International markets, accustomed to conceptional fashion shows, were quick to appreciate him. Last year Chalayan was appointed design chief of the TSE New York line, the luxury American label based in Manhattan. Ironically, the capital of commercial fashion was the first to acknowledge that he was capable of designing clothes to wear, and not just to gawp at in amazement. The high-street chain store Top Shop brought him in to design collections for them and, in fashion terms, you can't get more real than that.

Chalayan, who is now 28, has also been commissioned by the architect Zaha Hadid to design uniforms for the "mind" section of the Millennium Dome, and Turkish Cypriot Airlines have asked him to come up with a makeover for its flight attendants' uniforms, aeroplane interiors and logo. On top of all this, Chalayan's work is soon to be exhibited in galleries in Tokyo, Vienna, New York and Germany but he can't remember where exactly. Gradually, it seems, the world of design has embraced the Chalayan way of thinking: rigorous, and with a certain innocence not normally associated with London's pyrotechnic designers.

Hussein Chalayan's background is as unconventional as his take on fashion. The only child of Turkish Cypriot parents, he was born in Nicosia in 1970. When he was five years old his parents' marriage broke up. At 12 he was plunged into English boarding-school life at Highgate School in north London, an experience he likens to being in the Army. His mother and aunt always fly over from Cyprus for his shows, while his hotelier father has been known to put on the backstage buffets.

After A-levels, he abandoned his plans to study architecture when a friend told him he would be "building office blocks all day" and instead embarked on fashion. He did a foundation course at Mid-Warwickshire College in the genteel, tea-room town of Leamington Spa, where he came up with fabrics printed with various cuts of meat. Then came four years at London's Central Saint Martin's School of Art and Design, where one tutor told him to "bugger off and study sculpture". Tutors and students alike found his intense arguments about religion and identity overwhelming, if not irritating.

Today he is a star and everyone wants a slice of his action. The Chambre Syndicale, the French equivalent of our British Fashion Council, is trying to persuade Chalayan to abandon London Fashion Week and show his twice- yearly collections in Paris. He has not yet decided whether to go.

"I would like to make London work," he says. "It's more challenging than to move abroad, which is such a predictable pattern. And I hate the idea of being predictable," he adds, somewhat unnecessarily.

"There is something sacred about maintaining London Fashion Week, but when it boils down to business, it's a different issue." The problem, he says, is that the powerful, immensely influential American press bypasses London. "It's because there are no major advertisers based here, like Gucci, Prada and Versace. None of us [British designers] have that sort of magazine spending power."

What about Anna Wintour, the editor-in-chief of American Vogue, who surprised everyone when she showed up for London Fashion Week last month?

"She only came because she was hosting an American Vogue party," says Chalayan, refusing to acknowledge the impact of her front-row presence at his show. But even the apparently indifferent Chalayan was genuinely pleased when, in a rare move for Anna Wintour, she congratulated him afterwards backstage. This was indeed a mark of favour from the high priestess of Vogue.

The thorny issue of where Chalayan will choose to show in future is also dependent on the movements of his contemporary Alexander McQueen, who is rumoured (hysterically so, in London fashion circles) to be off to New York.

"If McQueen goes it will be more difficult for designers in London. But it's a question of discovering other designers. There's plenty of talent here, other than me and McQueen, who need to be given a chance." There's no hint here of insecurity. Chalayan knows he's made it.

He refuses to be taken in by the likes of Isabella Blow, the fruit-cake doyenne of British fashion, who likes to parade around in her favourite designers' clobber and also causes daily sensations with her avant-garde hats.

Ms Blow recently asked Hussein Chalayan whether she might borrow one of his sensational frocks to wear to the British Fashion Awards.

"It's fine," he replied, "just as long as you don't wear a lobster on your head."