Sylvie Guillem: Mademoiselle Non, the reluctant diva of the dance

Asked to name a top living ballerina, there's a good chance that even someone with only a passing interest in tights and tutus might well come up with Sylvie Guillem. She is very well known and yet a mystery. For a start, how do you pronounce her – Gwil-lem? Gwi-yem? Gil-lem? Even the French can't seem to agree. And why is she so very famous? She is not a spokesman for the arts on TV, she endorses no product, has never appeared in Hello! and is photographed very rarely. Nor has she been tempted to compromise her art to appeal to a wider audience. She doesn't need to. She is the most talked-about female dance artist since Fonteyn, and the most in-demand freelance ballerina in the world.

Last week Guillem appeared in a Frederick Ashton ballet at the Royal Opera House with the Royal Ballet. This week, she stars again at the Royal Opera House with La Scala Ballet from Milan. Not only has she chosen to dance five out of La Scala's seven performances of Giselle (a punishing work rate, almost unheard of in these stress-injury-conscious times), but the production itself is her own idea, which she has plans for making into a film. Here is a woman who is not content simply to be hired to display her accomplishments. She is making the world dance to her tune.

Sir Anthony Dowell, the outgoing director of the Royal Ballet, had a name for Sylvie Guillem. He calls her Mademoiselle Non, because, so he says, of the number of roles he offered her and she turned down. It is a tag which might also reflect her wilfulness in rehearsals. Her Giselle is a marvel of concentrated life and amusement and verismo acting, but it has increasingly veered from the Romantic context of the Royal Ballet's production. And she does not mince words in her disparagement, citing "stupid, senseless, empty productions of Giselle" as a reason why she went off and created one of her own.

Guillem's diva-esque manner belies a simpler background which she is reluctant to discuss. A concern with discretion pervades her private life. Nowadays she shares a west London flat and a house in Provence with her boyfriend, the fashion photographer Gilles Tapie.

Born in 1965 in Paris, Guillem was brought up in the 11th arrondissement, a working-class area towards the suburbs. Her father was a garage mechanic, her mother taught gymnastics to children, one of whom was Sylvie. With her slight, willowy build and extreme flexibility, she showed early promise on the gym mat and bars, and was shortlisted for the French Olympics team. But that dream soon receded when, aged 11, she was invited with several other young gymnasts to try ballet classes at the Opéra for a year, joined the Paris Opera Ballet School and at 16 passed into the Paris Opera Ballet company.

Her wayward path to the heights of ballet began when she walked out on Rudolf Nureyev at the age of 24. He had been her mentor, her coach and her Svengali. It was he who, as the newly appointed director of the Paris Opera Ballet, spotted the young redhead's potential and made her an "étoile" at the age of 19 – the youngest dancer to achieve the top rank in the 300-year history of the company. He was besotted with her talent. He created his Hollywood-style Cinderella for her in 1986 – one of his, and her, greatest triumphs in Paris. He chose her as his Giselle when he danced at Covent Garden to mark his 50th birthday. He taught her everything he knew. Then in 1989, wanting more control over her own career, she threw it all back at him, and marched off to London. Le Monde called it "une catastrophe nationale". Nureyev was devastated.

The 1990s was an uneasy decade for the Royal Ballet. But even in the company's darkest moments, when it was homeless and in the administrative mire, it was sustained in the knowledge that Guillem had chosen to anchor herself there. Why did she do it? She says she was attracted by the repertoire – some of her greatest moments on stage have been in the ballets of Frederick Ashton and Kenneth MacMillan that are unique to the company – and also by the freedom the Royal Ballet allows her. As principal guest artist, she is free to take on whatever other engagements she chooses, so long as she commits herself to a certain number of Royal Ballet performances, normally between 15 and 20 per season. She has also welcomed the very hands-off approach of Sir Anthony, an emotionally contained, even shy man, the polar opposite of the tempestuous, possessive Nureyev.

"When I am on stage," she says, "I feel completely free and just want to let go." She claims that she needs to feel nervous "to put me in an unstable state, to make me doubt, react, to make me live the role on stage". Terrifyingly, she also demands that of her dance partners. "If there is something we always do to the left, some nights I will go to the right to keep them reactive, alert." Little wonder her regular partners are so few.

At first, Guillem came across to the other dancers and staff at the Royal Ballet as arrogant and aloof. She claims she was shy and couldn't speak the language. But she didn't try very hard to be approachable, with her radical rock-chick fashion stance and marked disdain for small talk. With the other ballerinas, she didn't socialise, and she didn't play ball. When asked to donate their scuffed, discarded pointe shoes to be autographed and auctioned for charity, only Guillem refused, saying she wasn't going to pander to foot fetishists. It was a stark contrast to Darcey Bussell, the home-grown darling of British ballet, who has always been happy to oblige in any kind of fund-raising or publicity larks. People don't even ask Guillem any more.

The mixed reaction was shared by audiences, too. For years following her arrival in London, ballet fans were fiercely divided: those who saw in Guillem's extraordinary facility a powerhouse of new possibilities, and those who believed she turned a great art form into another branch of gymnastics. She has been cursed by ballet teachers around the world who have claimed that their most promising students inflict pain and even injury on themselves trying to hoik their leg up past their ear "like Sylvie". What is certainly true is that she has set a new benchmark for technical prowess within the framework of classical dance. Arabesques held higher and longer, leaps and twists more complex and more ferociously executed. Today's leading dancers can never properly be compared to great exponents of the past – the Fonteyns and Markovas – because in terms of sheer athleticism, they have left them far behind. There is no going back.

These days, the extreme physical feats are not the main draw for Guillem's admirers. At 36, she has developed into a luminous dance actress, whose intensely detailed portrayals have shone a piercing searchlight into the souls of Juliet, Manon, Giselle. She frequently leaves audiences tearful. She makes them laugh or grip their seats in fear. Almost infallibly, she draws them into the human predicament in a way that scarcely seems possible in a wordless medium such as ballet. Those with vivid memories of Margot Fonteyn were aghast at the news that Guillem was to tackle Marguerite and Armand – a ballet Ashton made expressly for Fonteyn at the passionate height of her partnership with Nureyev. But the depth and integrity of Guillem's interpretation swept doubts aside. Her command of detail is unparalleled.

Ross Stretton, the Royal Ballet's incoming director, has no doubt been advised by his predecessor on the best way to handle his hottest property. Kid gloves might come in useful. Or even a bullet-proof jacket. The most encouraging sign is that Guillem has signed a new five-year contract with the Royal. There are also hints that she might be mellowing a little. She has begun to give interviews. And at the farewell gala for Anthony Dowell she sent him a message saying: "I forgot to thank you for the nickname of Mademoiselle Non. But, as you know, I dislike not having the last word, therefore here are some yeses: Yes, I said 'No' many times. Yes, sometimes you were right."

Dance review, LifeEtc, page 10