"I heard about modelling and thought I'd give it a try," says Portia, one of Storm Models' sparkiest new signings. "So I got some pictures together and went in." It paid off. She may be at the very beginning of her career, but what a beginning it was. Portia's first big "go-see" – when models turn up to be cast by the photographer – was for a shoot with the fashion photographer Jez Tozer for The Independent as part of the current SHOWstudio exhibition at London's Somerset House. Being appraised, cast and eventually chosen all in the space of one morning, in front of a one-way mirror that allows the public to have a look at the process, can't have been easy.

But Portia's gamine looks mean that her strengths as a model chime perfectly with fashion's current tastes. She can veer from romantic to directional, via everything in between. "I did a shoot that was very sharp last week," she says, "with strong make-up and lots of monochrome. It was fun – I like being theatrical, but I prefer beauty shoots. I like something that's more natural." This is part of Portia's appeal: she is down-to-earth, eloquent and friendly. Aged 17, she is still at school, studying English literature, sociology and business studies, with a view to studying psychology at university. "I'm planning to take a gap year, do some travelling and spend some time modelling," she tells me. At Somerset House, Storm's Sarah Doukas was trilling about her young charge. "We have big plans for her," she said. "All the way to American Vogue."