Back in the Sixties, no one thought an `utter bimbo moron idiot' would end up running one of Britain's most successful fashion companies. Tanya Sarne tells Ruth Picardie how she pulled it off
Once upon a time there was a famous pop star called Mike Sarne. In the early Sixties he was bigger than the Rolling Stones - who supported his band more than once. His glamorous friends included Michael Caine and Terence Stamp, Julie Christie and Omar Sharif. When he went to Hollywood to become a director, he hung out with Roman Polanski and Warren Beatty. His first film , Myra Breckinridge, made the cover of both Time and Newsweek.

Naturally, Sarne had a girlfriend. Her name was Tanya and she was 23 years old. She modelled a little. She tried her hand at go-go dancing. She wanted to be an actress. "He was a pop star," says Grace Coddington, a friend of Mike Sarne's from the Sixties. "Pop stars have girlfriends. She was very pretty."

How the mighty have fallen. Thirty years on, Mike Sarne is nowhere. Myra Breckinridge almost ruined a Hollywood studio and his own career. Since then he's done a few commercials and worked in Brazil. But how his pretty girlfriend - now a sensuously beautiful ex-wife - has risen. Today, Tanya lives in a big house in Notting Hill with a recording studio on the ground floor, and has a seaside house for fun. She is friends with Charles Saatchi and Amanda Donohoe. And for the past 12 years she has run Ghost, one of Britain's most successful fashion companies. At the recent New York shows where British designers grabbed the most attention, Ghost was a star attraction. Fans of her fluid dresses include Nicole Kidman, Andie McDowell and Cher. Naomi, Helena and Linda do her shows in return for clothes, which they love to wear at home. Liberty, where a classic long shift costs from pounds 130 to pounds 250, devotes more space to Ghost than to any other designer. "Easy to sell," declares the store's merchandising director, Tom Logan.

How was this miraculous transformation effected? At first sight, Tanya Sarne, now 51, appears to be just another absolutely fabulous fashion victim. Her autumn '96 collection, she tells me at the company's HQ, a converted chapel off groovy Ladbroke Grove, was inspired by "sci-fi films. Anything from Star Wars to Forbidden Planet." "Intergalactic princess idea," pipes up Janet, her beautiful and desperately thin PR. "A wiggle in her walk and a giggle in her talk, makes the world go round," announces the meaningless blurb for the spring '96 collection.

Theatrical, funny, volatile, dedicated to late nights, Marlboro Lites, her 35-year-old ex-musician boyfriend, and connecting with her collection of driftwood, the word is that Sarne (pronounced with a silent "e", but don't call her Tarn) was the inspiration for Ab Fab's Patsy - rather than her old friend Lynne Franks. "I get frightened when I go to the shops," explains Tanya, who is exhausted by the shows, furious with the builders who have been in her house for 10 weeks, and devastated by the death of her dog, Woofy. "Miss Selfridge and Jigsaw and the high street multiples have brilliant clothes they do for next to nothing. I need loads of reassurance after one of those experiences or I get terribly rattled because I see someone's copied me identically and I throw 50 fits and want to sue them and kill them and throw bricks through their windows. Much better I stay away."

Look a little closer, however, and you'll find that Tanya Sarne, having imported Peruvian knitwear in the late Seventies, and later launched a sports wear line called Miz, is a brilliant businesswoman - not to mention the holder of a degree in history and psychology from Sussex University. Once housed in her old flat across the road - now home to her children Claudia, 26, a musician, and William, 23, who works in the film industry - Ghost is a multinational empire which wholesales pounds 6m a year. A long shift dress produced in 1994 by Marks & Spencer, which retains Sarne as a consultant, became a bestseller.

How has she done it? Her clothes, everyone in the industry agrees, are unique. "Beautiful fabrics," says Tom Logan, "Colours beautifully. Easy to fit." Their appeal is timeless," says Nicola Jeal, former editor of Elle. "What she has is a product, like Gap or Levi's, and there aren't many of those around. Disco girls wear her slips with nothing underneath. Other women wear her clothes to cover a multitude of sins." Even Grace Coddington, fashion director of American Vogue - a territory notoriously unsympathetic to British designers - remarks: "She's not really a strong designer. She just makes clothes that women like to wear." (Only in fashion is it possible to be praised by faint damning.)

Sarne's secret weapon is the fabric she calls the "Rolls-Royce of viscose", developed by one-time creative director Andrea Sargent, who Sarne recruited from Central St Martin's School of Art. The cloth is laboriously washed, shrunk, dyed and finished, which results in a uniquely flattering, glamorous look. Better still, the results - unlike silk - can be thrown in the washing machine and don't require an iron, hence the label's popularity with the Concorde set. "We want fabrics that breathe,' says Sarne, "that we can move in and feel comfortable in ... It has so much natural elasticity. If you get enormously fat one month you can iron it and make it bigger and bigger and bigger and then wash it and it will whoosh back again."

Sarne has marketed her product brilliantly. Instead of advertising - prohibitively expensive in America - she uses the New York catwalk and aftershow parties to generate word of mouth. Indeed, some insiders maintain the shows are merely an exercise in styling. Sarne herself admits the catwalk and buying collections may bear little relation - which means twice as much work for the team. Whatever, the formula works. The autumn '95 show was held in the Oyster Bar at Grand Central Station, where weary fashion folk revived themselves with seafood nibbles, and Sandra Bernhard (another Ghost fan) compered a supermodel-studded show. The first post- show party, a celebration of all things British, was attended by the nation's grooviest exports, from Quentin Crisp to Kate Moss; meanwhile, Christy Turlington slugged a photographer. The most recent party, held at a modish bar called Spy, raved on until 8am.

So much for the clothes and shows. The other ingredients in the Ghost cocktail is Sarne herself, a boss from hell or a great matriarch in fashion's family tree, according to who you talk to. "Mercurial, edgy, ruthless," says one insider. "The shows are pandemonium." "No one disagrees with her," said another. "She's a megalomaniac." Her old friend Lucinda Alford, who departed as fashion editor of the Observer to become creative director of Ghost, left after less than a season; neither party wishes to talk about what went wrong. At the after show party for spring '96, held on Hallowe'en, she was filmed shouting at a tearful Sofia Coppola, starlet and daughter of the film producer, who was trying to come in - horror - sans invite.

Certainly, Sarne believes in calling a spade a spade. Roman Polanski - a chum from the Sixties - she dismisses as an "Odd man. To say the least." Mae West - her daughter's godmother, who starred in her ex-husband's disastrous first film, was an "ignorant, vulgar woman". Another major Hollywood star: "one of the all-time great bores." Her refusal to suffer fools may be explained by the years she spent in Hollywood, isolated, penniless, with two tiny children, while her husband dallied with starlets in the back of a limo. "There's nothing glamorous about being locked up in a house in Malibu, away from society, away from what you know, being Mrs Michael Sarne. Not even having a first name to most people, and really having to do ... Meeting Paul Newman and Danny Kaye might not be as exciting as you think. They might turn out to be quite boring, narcissistic, self- centred people who are nowhere near as beautiful in the flesh as they are on film ... As a pretty young girl you are really treated like a complete and utter bimbo moron idiot and I think that's probably been my prime motivation - always having to prove that a pretty face can also think."

Similarly, she makes no attempt to conceal her theatrically bad moods. "Who did I shout at first?" she wonders cheerfully, when asked about a typical day. "I woke up extremely grumpy because there are builders in my house ... I then drove to work and lost my rag on the way. I'm only five minutes away, but the whole of Ladbroke Grove was blocked and the whole of Golborne Road was blocked. By the time I got here I was very wet and there was nowhere to park and the one space - our loading bay outside - was taken up by a little red something or other which now has a big notice on it I put on with glue, saying `PLEASE DO NOT PARK HERE'. "

Clearly, working with Sarne is a love-hate thing. If the chemistry doesn't work, there will be explosions: on the day I arrived, she pointed out in a stage whisper a young man who had just been fired. If it's love, however, you join the Ghost matriarchy. Ali started out 17 years ago as Sarne's nanny, and is now her pattern cutter. A cook prepares lunch for the staff every day, who eat en famille. Today, a two-month-old baby belonging to Angela Southwell, a design consultant, burbles happily on the floor. "I'm not nasty," says Sarne, "I'm just impatient with stupidity. I haven't got the time."

What of the future? Ghost menswear has been on the back burner for years (Mick Jagger owns a frilly lime green shirt) and Sarne hopes that market will soon be ready for her fabrics. There is a perfume in the pipeline, though she wants to wait until the cosmetics giant Coty - whom she fought and then compromised with over the name - launches its new scent, Ghost Myst. "Mind you," she says cheerfully. "Myst means shit in German."