Sophie Dahl: Who are you calling a vulgar pin-up girl?

The search for a new Marilyn Monroe is endless, and right now Sophie Dahl seems to fit the bill. It's not only that she's magnificently proportioned, has a complexion that glows from within and baby-blue eyes you could drown in, though obviously that helps. She also has a beauty that women as well as men love to love – an air of sexy, funny vulnerability and a sharp intelligence. It's a rare combination in a modelling world where there is traditionally a lot more beauty than brains around.

Dahl is fashion's most wanted new supermodel, the owner of the naked body which appeared in the notorious advertisement for Opium scent, now banned due to its high-octane sexiness. Too stylised to be mistaken for porn, it showed an apparently aroused Dahl in languorous and suggestive pose. Mick Jagger, we now discover, was equally appreciative. Dahl is rumoured to be the ageing Lothario's new girlfriend. The age difference shouldn't present a problem for Dahl, whose last boyfriend, the American actor Griffin Dunne, was 45.

The year 2001, we can be sure, will be a sunny year for her. Aside from her booming modelling career, she will appear in Al Pacino's new movie, People I Know. She has a small part in Woody Allen's next offering. "I don't want to talk about it," she says. "I might have been cut."

It is her gift to attract publicity without appearing to want it. Her relationship with Jagger has been quietly conducted. The pair met through his daughter Elizabeth, who introduced them in New York. Their subsequent pairing has caused outrage among the women in Jagger's family, and is said to be particularly resented by 28-year-old Jade Jagger, once a close friend of Dahl's. "All the significant women in Mick's life, including Jade and his two ex-wives Bianca and Jerry, have become jumpy about Sophie," said one friend. "She has upset the status quo."

Dahl's fondness for older men might be explained by her turbulent childhood and absent father. Her grandfather is Roald Dahl, who wrote his children's story, The BFG, for her when she was five. She counts Patricia Neal and Stanley Holloway among her grandparents. Her father is the actor Julian Holloway, her mother, Tessa Dahl, a former 1970s wildchild who gave birth to her daughter when she was only 20. The couple went their separate ways when Sophie was still a baby.

By the time she was 19, Sophie had moved 17 times and been bridesmaid to her mother twice. "All I wanted was a stable life," she once remarked, "but whenever I told Mum that she used to say, 'All right then, we'll get you a stable.' It became a sort of family joke." Behind the stylish front, playing the parent to her unhappy, alcoholic mother must have been extraordinarily difficult for her. While she stormed the modelling world, Tessa went what Sophie calls "a bit loopy. But the one thing I was sure of throughout her ups and downs was that she loved me."

For her part, Tessa, who has now won her battle with alcohol addiction and lives in her daughter's Battersea flat, is contrite. "Sophie has been incredibly generous. I'd behaved so badly that I didn't know if I would be welcomed back, but she has been so forgiving." Other friends have described impulsively generous gestures, like the time she gave a pensioner £100 in cash on Christmas Eve because they weren't going to be able to draw their pension until the holiday was over. Dahl is known to have a healthy sense of humour about herself and her career and makes an enormously entertaining dinner companion.

For all her Betty Boop prettiness, Dahl is far from ditsy, and nurses an ambition to become a writer. Before Dahl was famous for that ad, she was largely known, so to speak, for being big. She was discovered at 19 by the stylist and eccentric, Isabella Blow. Dahl was sitting on a doorstep crying after a row with her mother when she noticed a woman in a large hat trying to get herself and her shopping out of a taxi. Sophie rushed over to help, and Blow was smitten. "It wasn't just the face, it was the package: the cheekbones, the eyes, the bosom. I told her: 'I think you've got the most beautiful face I've ever seen and the body of a Playboy bunny. I'll make you a supermodel'."

It was Blow who introduced her to Sarah Doukas at the Storm model agency, the woman who had discovered Kate Moss. "I thought she was gorgeous and had this amazing presence." Then a dress size 14 and a bust size 38DD, she was shockingly large for a model. No one that shape had ever walked down a catwalk before, and the fashion world was transfixed. Large models were briefly in vogue, and Dahl was made the standard-bearer for "normal" women.Actually, Dahl was far from average, let alone fat. At six foot, with great legs and the face of an angel, she was scarcely a realistic role model for the rest of us. But realising that she was in danger of being pigeon-holed as an oversize model, she relocated to New York. Here she hired a personal trainer, lost a stone and a half, and secured her first prestigious contracts, with Versace, Yves Saint Laurent and Givenchy.

New York was not without its low points, however. "The lingerie castings were the worst," remarked Dahl. "The other models were all pert-bosomed glamazons, no bigger than a 32B. My cleavage made me look like a Penthouse refugee." It wasn't until she was "discovered" by the photographer Steven Meisel that the rock started to roll. Dahl calls it her "New York epiphany". "I'd been invited to this party given by John Galliano, and I was wearing this fabulous Gucci dress. Anyway, there I was with all these supermodels milling around and suddenly I spotted Steven. So I edged my way over and started dancing next to him. He introduced himself and by the next week he had photographed me for the cover of Italian Vogue."

News that she had felt the need to downshift was greeted with dismay by some women. Wasn't she betraying the sisterhood by dieting herself to modelling acceptability? It seems more likely that Dahl has merely come to a peaceful accommodation with her body. As a teenager, she has said that she was anorexic. Whatever her relationship with food and self-image, a disrupted and disrupting childhood can't have helped.

The new slimline Dahl makes the cover of this month's Elle looking poised and sleek. Anyone who has seen a fashion show will know that, in the flesh, the girls on the runway are peculiar-looking creatures. It's a look that needs to be photographed to be appreciated. Dahl, by contrast, is tremendously attractive in real life, and that is why she has a future outside fashion. As America's Allure magazine cattily put it: "Sophie is not a normal model. She is a vulgar pin-up girl who has managed to crack the market."

And that's her charm. Sophie is taken seriously as Sophie. She is not a model. She is a personality. Still only 24, she looks like one of life's survivors. She has the 21st century gift of re-inventing herself. But if she's really looking for a father figure, it might be wise to choose a more reliable one than Mick.