Size 14 and a Vogue model? Can it be true? It can, when the model in question is the supercharged scion of a family of extroverts
Once upon a time, a little girl called Sophie was immortalised by her grandfather, Roald Dahl, as the Big Friendly Giant's bespectacled sidekick in his children's book The BFG. These days, Sophie wears contact lenses and, at 6ft high in her stockinged feet with a voluptuous size 14 figure and a 38DD chest, she's more of a BFG herself. Normally, this would not be news. Most women in Britain are larger than a size 12. What is news, however, is that in an industry where being a size 10 is pushing it, Sophie is this year's hottest model.

Despite only embarking on her new career last December, 19-year-old Sophie has already entered the annals of modelling legend. Stories are told of how, for example, she was discovered sobbing in the street after a fight with her mother by Isabella Blow, the fashion doyenne and fixer. How Isabella then took her to a Spice Girls shoot to meet the photographer Ellen von Unwerth, who loved her look. How she was immediately signed up by Sarah Doukas (who famously "spotted" and signed up Kate Moss) at the model agency Storm. How she went on to appear in German Vogue (photographed by Karl Lagerfeld), Italian Vogue, Visionaire and Vanity Fair. And how, after working every day since her signing in January, no-one has asked her to go on a diet.

"It is hard finding clothes that fit," she sighs, as she tucks into a tuna salad in a cafe on the King's Road. "At the German Vogue shoot most of the clothes were undone at the back. In the pictures it looks like I fit marvellously into the beautiful Gianfranco Ferre outfits, when they were all held together with pins. Karl Lagerfeld was lovely about it though, so supportive. He kept telling me I looked like a Fifties Hollywood star."

That Vogue shoot was one of the very few to picture her with clothes on. The problem with photographing her is that most clothes look best on stick insects - her bosoms spoil the line and her extravagant Victorian figure just doesn't fit the mould that most designers have in mind when putting together their collections. And, so, the dance of the seven veils begins, with more and more clothes being rejected. Vanity Fair pictured her topless in big knickers and stilettos. Italian Vogue had her holding a carving knife and an ostrich-feather fan. Visionnaire and ID settled simply for splendid nakedness.

All of which goes some way to explain why the founders of Loaded cite her as "one of the girls of their dreams" and why Sophie appeared in the Mirror's Fashion Babes Special. So how do you photograph beautiful curves? According to the world's leading stylists, without any clothes on at all. "It is a bit ridiculous," she snorts. "In the Fifties, designers made the clothes on their models and women with a similar physique would go for the same look. Fashion should be about making clothes that make all women look beautiful, not making women starve so that they can fit in a size 8. I couldn't do it, I really couldn't be that size. I like eating too much."

Her grandfather, Roald, despite being thin, was a chocoholic. "We were all brought up on chocolate. He knew the history of every single chocolate bar, when they were invented, who they were invented by, what year. When he died, we buried him like a Pharaoh with all his favourite things around him - red wine, cigarettes, his snooker cues, and the most enormous box of chocolate bars, Twixes, Kit-Kats, Mars Bars, everything, just to keep him going 'til he got to heaven... I wish he were here now,' she adds, wistfully. "He would have found all this so funny."

His widow, on the other hand, strongly disapproves of her granddaughter's weight. Although Sophie is currently being hailed at her 12-year-old sister's boarding school as a positive role model, Patricia Neal "thinks I'm hugely fat. Grotesque. I remember going to see her in New York when I was about 15 and I was then about a size 10 - quite thin, isn't that? I walked in and she screeched 'My Gawd, you got fat!' and I said 'Oh. Thanks.' 'I mean, people told me you were getting fat,' she said, 'But I didn't know how fat!' I was a size 10! Can you imagine hearing that, aged 15?" She starts to giggle. "My grandmother is really awful sometimes..." She doesn't seem to mind.

Although she admits that most models would kill for the column inches her lineage grants her (Roald and Patricia on one side, the working-class comedian Stanley Holloway on the other, her father Julian, who was a staple of the Carry On films, and her mother Tessa, who became regular fodder for the gossip columns with her affairs with Peter Sellers and David Hemmings) Sophie claims to crave ordinariness. "We lived all over the place, life was unbelievably chaotic with my mum's love life. So, of course, now all I want to do is settle down and have some stability. My mother tells this joke about how when I was little I used to say, 'Mummy, all I want is a stable home!' and she'd reply, 'That's all right, darling, we'll buy you a stable.' Perhaps I shouldn't complain because it was a great preparation for what I'm doing now. I'm not frightened of any situation."

She finishes her cappuccino and lights up a cigarette. "It is great fun. I'd be lying if I said I didn't like all the attention I'm getting at the moment. But it would be nice, you know, if I were less of a freak show. The whole thing about my size is getting a bit boring. I'd much rather be treated like any other model - being booked because the client likes the look of me or being written about because people think I look beautiful, not because I'm size 14 with big tits."