Gugu Mbatha-Raw has got Hollywood at her feet. Currently filming with Willem Dafoe, the 28-year-old stunner also stars in Larry Crowne with Tom Hanks and Julia Roberts. And yet this time last year the Witney lass was a total unknown who’d never even been to America before. Katherine MacAlister manages to grab a quick chat with the actress before the rest of the world catches up.

Gugu Mbatha-Raw, is about to step on a plane for New Mexico to complete the filming of her latest movie, supernatural thriller Odd Thomas, when we speak.

She’s also in the middle of a massive press junket to promote Larry Crowne which will make her a global name.

But although she’s playing with the big boys and living the dream, no one has heard of this Oxford 28-year-old – until now.

Which is why the world’s media are working themselves into a frenzy over Gugu. Who is she? Where did she come from? How did she land a lead role with Tom Hanks and Julia Roberts in her first ever film? And how do you pronounce her name?

Luckily, we managed to sneak a quick interview with Gugu before she was let loose on the international press. So I can tell you that Gugu is pronounced Googoo, short for Gugulethu. Her father was a South African doctor and her mother a nurse. Gugu was born at the John Radcliffe Hospital and brought up by her mum in Witney. She went to St Joseph’s Primary School in Headley Way and the Henry Box School in Witney, but kept her acting as an extra-curricular activity, joining Oxford Youth Musical Theatre and volunteering every year for the Oxford Playhouse panto.

When she completed her A ‘Levels, she won a place at RADA in London, leaving home at 18 for the big smoke. Parts in Dr Who and Spooks came her way, but it was her role as Ophelia alongside Jude Law’s Hamlet, which brought her to the attention of Tom Hanks when it transferred to Broadway.

“I got a call from my agent saying Tom Hanks wanted to meet me in person,” Gugu tells me. “So I rushed to LA and we had a chat and talked about Shakespeare,” she smiles. “Tom’d seen my audition and liked it,” she adds unnecessarily.

So come on, what was he like? “Well it was the first time I’ve met anyone like that but he was so heart-warming. And the funny thing is that I felt as if l knew him already. But that’s his gift. He always plays the everyman with such warmth, and is such a genuine, nice guy as well as a real comedian,” Gugu laughs.

And what about Julia? “Well it was such a privilege to watch her work, because she’s such a great actress. And she’s classy and has done so many great films as well as having a family, she’s a superwoman,” Gugu sighs in admiration. “But most of my scenes were with Tom. Put it this way, you can see why they are both movie stars.”

So what would they say about her? Gugu squeals in horror at the thought. “Oh I hope they’d be complimentary, but we had a lot of fun,” she says diplomatically.

Gugu tells me all this, barely able to keep the excitement out of her voice, as if she can scarcely believe it herself, a far cry from the rehearsed monotone interviews with Hollywood’s leading ladies, who have long since grown bored of the public acclaim.

“It’s been such a whirlwind. I mean I had never even been to America before,” Gugu laughs, “so it’s all a bit crazy and exciting. And obviously working with Tom Hanks and Julia Roberts, who are movie legends...” and she falters, not knowing how to sum up how glorious the last year has been and how unexpected. “It’s been such an interesting and fun experience, which doesn’t happen very often.”

Larry Crowne, by the way, is a Tom Hanks written and directed film where Larry is made redundant, goes back to college and learns how to relive his life and have fun. While there he makes lots of new friends (Talia) who gives him a make-over and a life, and he falls in love with his teacher on the way – a very cynical and unhappily married Julia Roberts.

It’s set to be the big summer blockbuster when it comes out over here and over there tomorrow.

So what was Gugu’s character like? “Talia is fun and spirited. She meets Larry at a scooter parking lot and scoops him up. She is part of his reintegration and his new persona,” Gugu says, “so it was a great part and such fun to film. And when I wasn’t filming I spent the days with the stylist, trawling LA’s shops for vintage clothes, all very retro chic, which is something I like doing anyway.”

But it nearly didn’t happen at all. Firstly Gugu was in Egypt on holiday, “chilling out” after her taxing run in Hamlet, when she got a call from her manager saying she needed to get back to LA immediately. By the time she’d landed in the UK, the snow had arrived and she was stuck on the runway at Heathrow for six hours, wondering if she’d already blown it.

“I was thinking ‘it’s now or never. I either make it in time or I’ll go home on the Oxford Tube’,” she remembers.

“But I made it in time to audition for Tom. It was all very last minute, but that’s how things seem to work in LA and then a few hours later they rang and said Tom wanted to meet me and I got the part.”

Since then Gugu’s life has become more surreal, filming blockbusters, between magazine shoots and red carpet events. “It’s like being a kid again in the dressing up box,” she laughs.

But despite the dazzling film offers, parts and limelight, Gugu says her global debut has just made her appreciate home even more. “I come home to Witney whenever I can. My mum’s retired now so we can really enjoy the time when I come back, and we go for long walks. There’s nothing like the Oxfordshire countryside, and it really puts everything into perspective, and I still see all my friends who are all gunning for me.

“Because LA is such an urban metropolis, that I really appreciate Witney when I return, although it seems to change every time I get back – new mutiplex cinema, new shopping centre” she laughs. “But I love the tranquility and the people. And when I’m away I miss my mum and my family because being an actress is quite a nomadic existence, so it’s good to have a home to come back to so I can refuel and stay grounded.”