Claudia Schiffer: 'It's only on a shoot that I become sexy'

in an age where airbrushing rules supreme, we no longer expect celebrities to actually look like their magazine or screen images. It comes as a strangely reassuring sort of surprise then, when Claudia Schiffer looks, well, just like Claudia Schiffer. For a start, she is so tall that tilting my head to look upwards at her face feels like staring up at one of her billboards. Then there is her skin: taut, unlined, and as creamy and pale as a panna cotta. Her cheekbones are arched and cat-like, her eyes a bright ice-blue. Her long, thick blonde hair is straight out of a Timotei advert – it's the kind of thick, shiny mane that men want to tousle, and schoolgirls want to plait.

Schiffer is here in the Milan offices of D&G (Dolce & Gabbana's "contemporary line") – a chic, white-walled and floored building busy with Italians wearing all-black – as one of the faces of the brand's new perfume series. The campaign also features fellow "supers" Naomi Campbell and Eva Herzigova – who is swishing through the building, all long lean legs in spray-on jeans and peroxide blonde hair – and three male models. There are five unisex fragrances in the collection, and each one represents a different character trait. Schiffer is La Lune, a fresh white floral. "It's meant to be quite soft and sensual, mysterious, charismatic and also calming," explains Schiffer in a very un-self-conscious, matter-of-fact fashion, as if she was listing recipe ingredients. "In that sense it is like me because I am a very balanced person. I am calm most of the time." Indeed, the 39-year-old model has a very serene presence. As she talks, she gestures gently with graceful, balletic movements that bear little resemblance to the hyperbolic, verging-on-hysterical hand waving generally associated with fashion types.

This calmness is often mistaken for seriousness, perhaps a bit of squareness. While Schiffer's career might have been kick-started by her resemblance to Brigitte Bardot and her playfully sexual image, she is also known as being the sensible supermodel who has escaped the various drug habits, mental breakdowns, temper tantrums, court appearances, tempestuous relationships – or, gasp! – ageing that have afflicted various members of the supermodel gang. Schiffer hasn't had any major relationship scandals – although her pairing with perma-tanned magician David Copperfield in the Nineties was a bizarre match which met with some surprise, not to mention sarcastic headlines about how the model was under his spell. She is very anti-drugs, as is husband Matthew Vaughn, the film producer, director and mate of Guy Ritchie, with whom she was set up by friends in 2001.

"A lot of people say I am serious, but I don't think I am," Schiffer continues, in serious tones that show exactly why she has this reputation. "Also, people sometimes say I am reserved, maybe because Germans can come across as quite cold when actually they are not. The way Germans work is that they are slow to warm up but when they do they are your friend for life and very loyal."

When schiffer began modelling, after being spotted in a Düsseldorf nightclub aged 17, she was "so shy" and "would blush bright red if I ever saw anyone looking at me in the mirror". She remembers "an editor at Vogue who called me the girl with the woollen underwear. It was a symbol of the girl from the small town, the Heidi in the mountains thing. She meant that because I was shy I wouldn't arrive at the job dressed in a sexy way. Instead, I would be in a big baggy sweater and jeans." Did it bother her? "Oh no. I would rather that than have people say, 'Oh she's so scandalous'," she shudders.

While the other models exuded confidence, for Schiffer, "it was only once I was in front of the camera that I would cross the line and become sexy. When I'm on a photo shoot I'm not shy at all. I take my clothes off and strike very sexy poses." The secret to Claudia's longevity is that she has taken charge of her image and her career by compartmentalising herself (and by fiercely guarding her privacy: in 2006 she successfully sued the publishers of a book by her former cook for using an unauthorised quote). There's sexy Claudia, who the glamour-hungry public get, the polite professional – she's in this mode today – and the private, candid Claudia, that only her friends and the closest colleagues see. Clearly, the latter was on display for the D&G shoot, which involved the photographer Mario Testino ("He's fun, he's got a great sense of humour, he has lots of stories..."), Naomi Campbell and Eva Herzigova. "I see Naomi a little bit less," Schiffer admits, "but I see Eva quite a lot – we both live in London now. If you haven't seen a girlfriend for a long time it's like, Oh my God, we have so much fun."

While her self-containment might not provide the scandal and behind-the-scenes titillation that a society run on gossip craves, it's kept "Brand Claudia" as untarnished and lustrous as ever. When she poses for a portrait, she obligingly walks over to a wall where the photographer deems the light to be best, and right on cue Sexy Claudia appears. She slightly closes her eyes, in a sleepily indolent expression, tips her head coyly to the side and poses for all she's worth like a young Bardot on the Croisette. The transformation is mesmerising.

It's this type of charisma that has landed Schiffer more magazine covers than any other model. She scooped her first major campaign for Guess jeans just a year after being spotted; Karl Lagerfeld made her his muse and persuaded her to make her catwalk debut at a Chanel couture show in 1990; and in 1992 she signed a record-breaking $10m contract with Revlon. The same year she appeared on the cover of Vogue's 100th anniversary issue alongside a gang of supermodels including Naomi Campbell, Christy Turlington, Cindy Crawford, Karen Mulder and Linda Evangelista. The supermodel era was in full swing and these women were like fashion's rock stars. "There were just so many crazy moments back in the early Nineties," recalls Schiffer. " I remember coming off the catwalk at the end of the Chanel show and not being able to change my clothes because there were so many people who wanted to come and talk to me. Fans, press, paparazzi. Someone had to find me a corner where I could hide behind a blanket; I couldn't leave without bodyguards to escort me. I thought at that moment, this is different, this is not normal." This is the only time she seems slightly lost for the precise words to express herself, and to convey the sheer exhilaration of the supermodel phenomenon.

In some respects, though, the wholesome girl from a small town near Düsseldorf who had wanted to follow in her father's footsteps and become a lawyer, had a calmer time than most. She certainly wasn't gulping champagne backstage or on the dancefloor until dawn. "I personally didn't go to lots of parties," she says. "I think the shyness actually protected me from lots of things. That's probably why I have only had good experiences in modelling because I never had that moment where someone offered me drugs or something bad could have happened." Of course, all the manners in the world couldn't entirely protect innocent little Claudia from all the slights and hurts of the big bad fashion world, and eventually the supermodels fell out of favour, supplanted by the dreaded grunge. In 1996 Lagerfeld unceremoniously dropped her as his muse, and although Schiffer had been warned that he would, and had herslef seen Inès de la Fressange dumped, she rather trustingly felt that Lagerfeld was too sweet to do it to her.

However, just over a decade later, fashion's wheel of fortune turned back round and in late 2007 Schiffer returned as one of Karl Lagerfeld's muses and appeared in a Ferragamo campaign. Last season she was a face of YSL and she is also fronting Alberta Ferretti's first perfume. Not that Schiffer hadn't been busy in the intervening years – with her personal life, for one thing. She married Matthew Vaughn in 2002 – he gave her a tortoise instead of an engagement ring; she wore a "fairytale" Valentino dress and the ceremony was followed by a 1966-style "Germany vs England" friendly game of football, with Boris Becker the captain of Schiffer's team. The couple now have two children, Casper and Clementine.

Why does she think that the supermodels are in demand again? "One of the logical reasons..." (Schiffer is always logical) "...would be that we sort of went away at the same time and most of us had kids at the same time and then we sort of came back. We've also worked for such a long time, we are reliable and professional and you know what you'll get." Designer Stefano Gabbana thinks that, "certainly after them, nobody was able to equal the fascination they hold," and Domenico Dolce that, "their fame has not diminished in any way along the years. In uncertain moments we look up to the things that make us feel safe. Designers recover their heritage and supermodels are definitely a part of it."

Schiffer has worked with the designers for over 20 years, since back "when they were just starting in Milan and everyone was talking about them". During that time, Schiffer has "changed so much" and so has the modelling industry. "It's very difficult today for girls to become supermodels," she says, revealing no qualms about the term. "There is a lot more competition, a lot of countries in the East have opened up so there are many more models than there were in the Nineties. Now they have to compete with famous actresses but also with, say, reality stars to be on the magazine covers. I don't think it's impossible but it is very hard."

She would advise today's young models that, "to make it you really have to commit. You can't think, 'Oh I will be going to loads of parties with a little bit of modelling.' No. The work is number one and it's about whatever it takes to do the work." Now that she's almost 40, does the industry's obsession with youth make her anxious about ageing? After all, this is a woman who has said that she felt old in the Nineties when grunge came along. She would "never say never to surgery" but hopes "that it doesn't come to that. I'm just a healthy organic person, so the idea of doing something to my skin that's not organic, that doesn't really agree with me – and I'm very squeamish. The other thing is that I have a lot of friends my age and we are getting older at the same time and at the same rate more or less."

When I ask Schiffer if she has any vices, she says, "I do love a Starbucks Frappuccino." I assume that she is joking with me, but no, this really counts as a vice in her book. "People have seen me OD on those. On a really bad day I would have one in the afternoon as well and my heart will really be racing. I am reducing it now and seeing it as a treat." It's not that bad a habit surely? "Well it has a lot of caramel and sugar in it." Anything else? "When we meet up with friends I will have a glass of red wine. The weekend is the time when my husband and I say, OK, we will have a slow roast of some kind and during the week we try and be very straight and healthy." She only started drinking when she was 28; has she ever been drunk? "Of course, but never so drunk that I can't remember anything from the night before." Fair enough. When, at almost 40, you look like a cross between Heidi and Brigitte Bardot, can pick and choose your work (Schiffer recently announced she is done with the catwalk), have a happy marriage, two cute-as-a-button children, a country pile in Suffolk, a smart west-London base and more homes around the world, not to mention an art collection which includes work by Damien Hirst and Andy Warhol, why would you want to forget a minute of your perfect life?