Supermodel Jourdan Dunn, face of Gap, veteran of US Vogue, and most talked-about model of spring/summer 2008 Fashion Week (in which she walked in an incredible 75 shows including Louis Vuitton and Valentino) has something she’d like to put straight. ‘Everybody says I was spotted shopping in Primark. I wasn’t shopping. I was with my friend: she wanted to go in, I wanted to go home – and we were just mucking about in the sunglasses section.’

It’s an important distinction when, like Jourdan, you’re 17. The tale of the Greenford schoolgirl, discovered by top agency Storm Management in a Hammersmith store in 2006, who goes on to become one of the biggest new models in just two years is too pat for her. When approached by the scout, Dunn knew the Storm name from magazines and America’s Next Top Model (’I thought: Kate Moss!’); she instantly rang her receptionist mum, Dee, whom she and her two younger brothers live with in west London – ‘She was screaming, I was screaming.’ But she wasn’t shopping in Primark. She was mucking about . She’s still unjaded enough to care about truth rather than received wisdom.

Dunn is a fashion star, but first and foremost she’s a teenager, and a very smart one. She’s articulate and observant not only about her own history but about the fashion industry. At London Fashion Week in February, her comments about race made the news. ‘London’s not a white city,’ she told the press. ‘So why should our catwalks be so white?’

Race replaced weight as the story of Fashion Week and anonymous ‘fashion insiders’ opined that the industry had to bow to customer demands: customers who apparently demand white, thin, blonde models. ‘The way people said I was stupid made me feel horrible,’ says Dunn, ’saying that fashion’s just a business so they need to use models who sell things.’ Seeing Naomi Campbell and Tyra Banks when she was growing up made her believe maybe she could be a model. It’s hard to think of other names who could have inspired a teenage black girl. ‘I don’t see a change. It needs to be said because I think about these things and other girls do too.’

Dunn agrees with Campbell’s mooted plan to establish a modelling agency that will promote different races. ‘I’m really ambitious. When I go back into education, I’m going to do business studies. Naomi’s idea is good; I’d do an agency for black girls – and Asian and Spanish, because there aren’t enough of them on the runway either.’

Dunn proved her point when, the week after her comments in London, she became the first black model on Prada’s catwalk in Milan since 1997 – when Campbell walked for the label.

It’s going to be hard for Dunn to avoid the subject of race now, but it won’t be the only reason she’s famous. ‘Not many British girls make a mark on the fashion world,’ says Sarah Doukas, Storm’s MD. ‘When she went to Paris Fashion Week after the Prada show she got standing ovations from the big fashion houses. Jourdan’s also rather wonderful – she’s strong-minded and funny. She has us in stitches.’

Dunn finds it hard to be away from home – ‘I miss out on getting on my brothers’ nerves, so when I get back I have to get on their nerves on purpose to catch up’ – but she’s very happy working as a model (though she misses her drama studies and talks about opening a performing arts school one day). ‘My mum used to come on castings with me – I was scared because there were all these models with their nice shoes and handbags. But now if I don’t get the job it doesn’t bother me. You can’t take it too seriously.’

At the Observer shoot, unlike many models, she takes the time to sift through the clothes rail because she’s genuinely interested. She sits patiently through hair and make-up. ‘I like seeing how I can look in a photo,’ she says over the blast of the hairdryer. ‘I like having spikes coming out of my head or being in something I’d never wear. It’s fun looking at myself in a different way.’

Supermodel, international catwalk star, accidental spokesperson on race, teenager mucking about in Primark … Hopefully everyone will find a different way to look at Jourdan Dunn.