Agyness Deyn's Electricity: From the cover of Vogue to film star

Agyness Deyn camped out in a doctor's surgery to prepare for her latest film

Bright spark: Agyness Deyn in 'Electricity'

The Agyness Deyn whom I meet in a viciously air-conditioned Mayfair hotel room is not the Agyness Deyn who jumped out at you from Burberry billboards, covers of Vogue and Grazia magazine, and TV adverts almost 10 years ago. The peroxide elfin crop, the garishly coloured clothes, the cool model aura have all disappeared.

This Agyness gets up to greet me dressed all in black and beige, mousy brown hair grown to her shoulders and a much warmer sparkle in her eyes. Her mum, Lorraine, is joining us, with Deyn bashfully explaining, "Now I live in Los Angeles I really miss my mum so much, so we're spending as much time together as we can."

Having unofficially retired from modelling five years ago, Deyn is now set to make her real acting debut with a leading role in Bryn Higgin's Electricity in which she plays a severely epileptic woman, Lily O' Connor, who is searching for her long-lost brother. It's the morning after the London Film Festival premiere and she's finally allowing herself to be excited. "We filmed it 18 months ago, you don't know what the reaction is going to be while you're making it," she says in her Lancashire lilt. "Then, last night at the screening I had people coming up to me afterwards and saying, 'I have epilepsy. Thank you for this film'."

Deyn went from working in a Rossendale chip shop during her teens to becoming the most in demand model in the world: the Cara Delevingne of the Noughties. She was on every red carpet, every guest list, in every ad campaign and then suddenly… nothing. The 31-year-old – who was born plain old Laura Hollins – has claimed, until now, not to have quit modelling altogether. But aside from the odd paparazzi shot of her food shopping in Los Angeles, where she lives with husband, Giovanni Ribisi (Phoebe Buffay's brother Frank on Friends), Deyn had totally taken herself off the showbiz map.

The role of Lily is a tough one, particularly for Deyn, who has had no professional training as an actor, though has filmed a couple of very minor roles in indie movies. Portraying someone with epilepsy is something that took a lot of preparation. She desperately wanted (and had to) get it right. "To do that justice for the people who actually have it was important. I read a lot, I watched a lot of documentaries, YouTube clips," Deyn says. "I met this doctor – he's a specialist in London. I basically camped out in his office. I was going there on his lunch breaks and he would go through footage with me and help me really understand it on an intellectual level but also an emotional level."

Camping out in a south London doctor's surgery is a far cry from a modelling gig in New York for a six-figure fee, but Deyn claims she is more than happy with her lot these days: "I do look back at that time fondly and I feel like, wow that was so fun. It was exciting and you know it's part of my life which was a catalyst to a lot of other things. But I don't miss it."

Deyn won't discuss her marriage, but she does admit that she's more comfortable in her own skin these days. "I feel more myself, not because of the place [LA] but because of where I am in my life and what I'm doing." Deyn and RIbisi's relationship brought with it a maelstrom of press attention. Newspapers and magazines were once again intrigued by the model and her shock wedding to the actor, not just because of his fame from Friends and films like Lost in Translation but because he's a Scientologist. Deyn has simply said, "People ask me about it. Maybe it's because it's a new religion and people are curious about it. I don't know– my husband is an amazing man."

Like most celebs, Deyn claims not to read the papers: "You can kind of open Pandora's box. If you're true to who are it shouldn't matter what is written." She will only admit that Ribisi gives her advice as an actor. "Definitely, obviously we talk about it but we keep it very separate from our lives together too. We're both very private…"

You get the sense she has had a crash course in media training, picking her words very carefully and dodging questions. You can sense the LA influence on her speech, not in accent but vocabulary. Deyn talks about "her truth", "growing" with the film crew, "self-fulfilment", things that the 13-year-old her who worked in the chippie might have screwed her face up at. One thing she's clear on, though, is that her modelling days are well and truly behind her. When asked how she would classify her profession she is now certain. "I'm an actor," she says firmly.

Deyn outgrew modelling, she was desperate to use her brain and become a "three dimensional" person. She exhales before explaining, "I'd done it for so long, 12 years is a long time. I was exploring different ways to be creative and keep my life more exciting and challenging. I was looking for something I had to have to fight for and grow in and learn. So I started doing short films and that was when I really started to be three-dimensional and communicate to people."

And her ambition is evident. The indie Brit flicks (such as Pusher in which she played a stripper) have been a great training ground, but she has set her sights on bigger things. "It's just happened that all the films I've been doing are English indie films. But, yeah, I'd love to do Hollywood films. I'm open to anything." Her dream co-star? "Meryl, obviously". Her dream director? "Steven Spielberg." Big dreams. But if Deyn can go from a chip shop to the cover of Vogue, who's going to stop her?.

'Electricity' is released on Friday