Nik Cohn will always be best known as the man who wrote the short story on which the blockbuster disco film `Saturday Night Fever' was based, but he considers his other books and journalism more important.
AT THE party to celebrate the premiere of Saturday Night Fever, The Musical, Barry Gibb of the Bee Gees offered a special word of praise for Nik Cohn. "It's all your bloody fault, isn't it?"

Indeed, it is. The keening harmonies of the Brothers Gibb, a million naff dance routines by medallion men under the illusion that they were John Travolta in a white suit, tens of millions of records sold and cinema seats filled - it was all down to Cohn and Another Saturday Night, the short story he dashed off back in the mid-Seventies on which Saturday Night Fever was based.

Just as the Bee Gees and Travolta were to find that film a mixed blessing - the singers have never shaken it off and Travolta only laid to rest the ghost of the protagonist Tony Manero after Pulp Fiction - so Cohn finds himself invariably described as the man who wrote it, though he didn't write the screenplay ("I had a go, but my script was the alpha and omega of turkeys") and considers his other books and his journalism more important.

"Fever has always been odd for me because it wasn't a big deal in my writing life," he says. "It was a small story. I was finishing a novel at the time, King Death, which I was convinced was the important thing, whereas it was the worst thing I ever wrote. It confirms what I have always suspected, that we have no idea what we're doing at the time, in life, in love or anything else."

What remains doubly odd about Fever is that although Cohn set his tale in Brooklyn, it was based entirely on his experiences of London mods back in the mid-Sixties. He simply grafted their weekend rituals - the narcissism, the dancing, the rivalry - onto Italian New York. Even the mod argot stayed intact, after all, no-one in Brooklyn ever talked abut "being a Face", but native New Yorkers would still ask Cohn how many years of research it had taken to capture their experiences so acutely.

"I touched on an archetype," says Cohn. "Disaffected youth is disaffected youth - that lad standing there in Nowheresville thinking there has to be more to it than this. Fever is about that hunger. What was different was that previously people always became rock stars to escape. Fever concentrated on tiny stardom, the idea that you could satisfy that hunger on your own turf."

Cohn was 30 when he penned Another Saturday Night, but already a writer of repute. In the Sixties he had become a cause celebre, thanks to the novels he had written as a teenager - Market and I Am Still The Greatest Says Johnny Angelo - and Awopbopaloobop Alopbamboom, his 1969 rock history which even now remains one of the definitive pop texts.

Tart and informed, his writing captured the mythology and texture of music and youth culture in snappy, waspish prose. The same quality informed his journalism for the Observer and the Sunday Times, which chronicled the pop decade in all its peacock glory, though as Cohn points out "Swinging London was tiny - 500 people and three nightclubs. In Muswell Hill it was still the 1950s."

Cohn quit Britain for New York in 1975, though he remains a regular visitor. Today he is in senior statesman mode. Ensconced in a discreet but plush West End hotel, up at the dark-blue end of the Monopoly board, he is burly, bearded and dapper, draped in a lovat suit topped off by correspondent shoes at one end and a large fedora at the other. He has always worn hats, he tells me. Back in the Sixties, it was floppy, plum-coloured velvet jobs to go with his white suit. "Now the mere act of wearing a hat causes more outrage than wandering through St James's Park naked."

Along with music, clothes and style are one of Cohn's enduring fascinations, though I am disappointed to find that he is not responsible for putting Travolta into a white suit for Fever. "I stopped wearing them when Tom Wolfe started wearing them. There was enough guff about me being the English Wolfe and the suits would have made it seem like I was a wannabe, whereas I hated him," he laughs.

Cohn was brought up in Derry, where his father, the celebrated historian Norman Cohn, was a university professor. But academia held no interest for a young man who had fallen in love with rock'n'roll. "And what do you do when you're completely unskilled and averse to work?" asks Cohn. "You become a writer."

Cohn still lives contentedly in New York, an American citizen with an American wife - "I like the intensity of New York. England goes in phases, but America is never flat" - but in the past few years his visits to the old country have become more frequent, ever since the Cohn antennae started to pick up new and interesting signals from the grass roots.

"There's a false buzz about Cool Britannia, which is a PR job, and there is the real buzz. You only have to walk through Soho to feel that something is popping," says Cohn, whose present obsession is the Asian drum 'n' bass scene, the nexus of musicians such as Talvin Singh and Nitin Sawnhey and clubs such as Anokha and Swaraj, busy forging the sound of millennial Britain. "I find endless fascination with new movements because it's always new and always familiar - Awaraj could be mod or could be Tony Manero."

Cohn's celebration of Anglo-Asian drum 'n' bass will doubtless feature in the book he is now completing, Yes We Have No..., a profile of modern Britain seeded by his Guardian columns of the same name.

There are, he thinks, two Britains; the official state and "the republic", a term he picked up from a King's Cross hustler to describe "the amalgam of immigrants and English and Irish who have fallen off the tree or are clinging precariously to one of its boughs. It is a very large proportion of the country - perhaps as much as 40 per cent, according to Will Hutton. Yes We Have No... is a book about life in the republic."

His other current project is Twentieth Century Dreams, which returns him to his collaboration with Belgian artist Guy Peellaert. In 1974 the pair produced "Rock Dreams", a brilliantly realised set of fantasy pop portraits in which, for example, Rod Stewart is depicted as drunk and disorderly between two coppers and the Stones as S&M transvestites.

The new book extends the concept to the century, "beginning in 1914 with Rasputin and ending in 1999 with Yeltsin", says Cohn, whose favourite image is for 1964, showing Muhammad Ali driving a convertible down the New Jersey turnpike with his arm around Jackie Onassis.

It's very different from Cohn's most recent work, Need, a novel which attempts to apply the techniques of magical realism to contemporary New York. Cohn calls it "an apocalyptic metaphysical novel about the journey of the soul", which is not what you expect to hear from a Little Richard fan who cites as his most important literary influence Mr Jelly Roll, the autobiography of the New Orleans jazz man Jelly Roll Morton.

"I can't claim to be a Catholic," says Cohn, "and I don't much like the official church, but I've always been interested in the mysteries that lay behind the church's daily workings." It's a remark that brings to mind his father Norman's recently reissued book, The Pursuit of the Millennium, a seminal text, on the mystical and apocalyptical currents of the Middle Ages. "In every writing life there should be one book that's completely internal," says Cohn. "Need is very uncommercial but it will always be my favourite book."