Keira Knightley

Don’t forget, instructs a publicist as she ushers me into the sumptuous suite at Claridge’s where I’m about to interview Keira Knightley, you’re not allowed to ask her anything personal. Just stick to Atonement, OK?

This is to be expected — Knightley is apparently averse to journalists, after various speculative articles about her weight (or lack of it) and her love-life (with Rupert Friend, who appeared alongside her in Pride & Prejudice). Hence the deal is that she’ll talk only about her role in Atonement. So I’m momentarily nonplussed by her opening gambit, in the first few seconds of our encounter. “I haven’t actually seen the finished version of the film yet,” she says, “but I hear it’s very good.”

She’s sitting straight-backed on a sofa, and her tone is that of a nicely brought-up English girl, fresh out of boarding school, making polite conversation at an afternoon tea party. But the distance she puts between herself and the film that she’s starring in and has come here to promote is oddly disconcerting.

It’s not that she doesn’t like Atonement — a little later she mentions its director, Joe Wright, with whom she previously worked on Pride & Prejudice, and says, “As far as Joe and the team are concerned, this film has gone to a very mature place; there’s a certain confidence about it.”

But she seems resolutely determined to say nothing that might be construed as boastful; nothing that alludes to what has brought her to this room today, as if the very mention of her fame or success would be ill-mannered. It’s a peculiarly English trait — a self-deprecation that can also serve as a kind of defence mechanism — and yet it’s the absolute opposite of what Knightley does on screen (whether in Atonement, in which she dazzles as a luminous ’30s heroine, or her Oscar-nominated performance as Elizabeth Bennet in Pride & Prejudice, or as the feisty female lead in Pirates of the Caribbean).

In front of the camera, her charisma and beauty are strikingly evident.

Off-screen, she’s just as beautiful — big brown eyes, long dark lashes, glossy hair tossed back to reveal those famous cheekbones and the even more famous pout — nevertheless, she seems oddly lacking in confidence.

As it happens, she behaved in a similar way the last time I met her, three years ago, when she had just turned 19 and was already famous for her role as a tomboyish footballer in Bend It Like Beckham. She masked her beauty with the standard uniform of a grungy London teenager (ripped jeans, hooded sweatshirt, unbrushed hair).

Today she’s far more polished — her hair and make-up are perfect, and she’s wearing Chanel platform heels, fashionably high-waisted black trousers, a charm bracelet that belonged to her grandmother and a red stripy top that reveals her figure to be enviably slender, rather than scarily skinny. She looks every inch the adult professional, but, even so, her conversation is scattered with descriptions of herself as vulnerable or anxious. Thus there’s an edge of uncertainty in her tentative selling of Atonement.

In fact, the film seems likely to be a big success, both critically and commercially, and Knightley performs with the poise of a grown-up actor hitting her stride; not that you’d guess it today, with her murmurs that she’s “still learning”.

“I think, with this film, it was the first time I felt comfortable,” she says, sounding somewhat uncomfortable, “and that I could possibly do it, and that maybe I wasn’t just there because I was a pretty face, and that I could actually give something to it.”

But did she really feel so uncertain before? “Very much so,” she says, twiddling a lock of her hair between her fingers. “Bend It Like Beckham came out when I was 17, and I only saw about two reviews, but they both said, ‘She’s pretty but she can’t act for sh*t.’ It’s only when I look back on it that I realise how much it really did affect me, because I didn’t have very much self-confidence. You already feel unsure of yourself, and then you see your worst fears in print. It really knocked me — which is why, I think, I was working, working, working... trying to run away from the fact that I thought I couldn’t do it.”

It must have been hard, I say, growing up in public, in the glare of celebrity culture, dissected for popular consumption. She nods her head, and then a small note of defiance creeps into her polite voice. “It’s very strange, because you’re meant to be very grateful — it’s meant to be everything you’ve ever dreamt of. But it’s bollocks. Being famous wasn’t what I aspired to.”

Knightley started working at seven years of age. By the end of last year, after finishing Atonement and the final film in the Pirates trilogy, Knightley decided she needed a break. “It was the first space I’d had since I was 17,” she says.

She gives a rare moment of insight into her decision to take five months off. “It was seeing that my friend’s hair had grown — it was that simple. It felt like yesterday we’d been at school but, actually, it had been four years and I hadn’t been at her last four birthdays. I realised, f**k it, life’s short. What are you doing? If the work stops, it stops — there’s always something else. Just chill out.”

It’s at this moment that her publicist arrives and signals that it’s time to bring the interview to a close, and Knightley bursts out laughing. “Just chill out!” she says, again, as if it’s an order and it’s hard to tell whether she’s mocking herself or the situation in which we find ourselves.

Either way, she looks lovely when she laughs.