“And her style of acting is fantastic: very natural, very real, and very much based on a foundation of truth.”So, the rustle of posh frocks, the roar of the crowd, the smell of the paparazzi – was the premiere a good night out? Garai pulls a face and sighs. “She is luscious and intelligent but has no vanity about her,” the director says. The film – which opens in the UK early next year – is a handsome epic in which Garai more than holds her own against stellar, established talents such as Witherspoon, Eileen Atkins, Bob Hoskins and Jim Broadbent.Having been impressed with her turn in Daniel Deronda, Nair cast Garai without an audition. Garai doesn’t do movie-star fuss.She’s just back from the New York premiere of Vanity Fair, the new film by Mira Nair (Monsoon Wedding), in which she stars as best friend to Reese Witherspoon’s Becky Sharp. And yes, she is wearing big, glam sunglasses but only because the sun is shining in her eyes.She has two agents and the requisite high-powered Hollywood publicist but has travelled here from her single-person’s flat in London’s Shepherd’s Bush on her tod. We’re eating fabulous food on the terrace of Inn The Park, Oliver Peyton’s swank new eaterie. Garai, a committed foodie and enthusiastic clipper of recipes from magazines, has been dying to come here for ages.

She would have a glass of wine but she has a driving lesson later So she chain-smokes Marlboro Lights instead. And now, thanks to two new films – Inside I’m Dancing and Vanity Fair – Garai is about to graduate to the premier league.It is a sunny late-summer’s day in St James’s Park, central London. She has the fearsome skills to match her fearlessly opinionated character and a smorgasbord of character-building roles behind her – from the sublime (her on-stage role as James Joyce’s daughter Lucia in the West End production of Calico, and last year’s excellent film, I Capture The Castle) to the ridiculous (Dirty Dancing 2) via the obvious (the obligatory period melodramas, in her case Daniel Deronda and Nicholas Nickleby). An avowedly over-earnest young woman whose says her ideal film role would be to portray proto-feminist author Mary Wollstonecraft.As with Samantha Morton, one of her acting role models, Garai’s off-message pronouncements are not the outpourings of someone trying to gain attention by any means necessary. But rather than coddle her, this background has fired her up. She’s a full-force blast of passion, enthusiasm, soapboxing and tangential chat, with added swearing – she uses the F-word like most people use the telephone.Thank the Lord. A beautiful young British actress with something to say for herself.

Someone not afraid to criticise the beauty parade that constitutes much of the life of a young actor, male and female, nor to confess to her own professional missteps. Aged 17, she even did the modelling thing (a soul-sapping, penurious slog, she says). As she’s the first to admit, she’s a standard representative of the newbie British acting ranks: product of a public school and a “secure, secluded, well-educated, middle-class upbringing”. They’d do the job, smile and look pretty on the cover of Teen Vogue. There I am, 135 pounds and trying to make art! I was so wrong for it!”This is the kind of talk which, it will transpire, is typical Garai.