Little Miss Sensible

Olivia Williams emerges from her changing room in a figure-hugging, slinky Catherine Walker number. In her husky authoritative voice, she explains to the make-up artist where to apply shadow around her clear grey-green eyes and which gloss to paste on her lips.

She perfects a series of poses, a pout here, a smoulder there, and then a dazzling smile. The shoot is over in a flash with no fuss and minimal direction.

There's something about her that puts you in mind of a youthful Glenda Jackson: self-possessed with a touch of the headmistress about her. She'd make a perfect Elizabeth I.

'Sorry. I may seem obsessive, but you know that awful feeling when you go to the hairdresser? You are staring into the mirror and you can see them destroying your hair. Imagine how it feels being squeezed into a horrible dress and having ghastly make-up plastered all over your face and then having to smile for a camera. It just works better if I organise it all myself.'

Which could be said of her entire career. This is, after all, a Hollywood actress who still refuses to hire a publicist; who can happily wander through her local Safeway unrecognised even though she starred as Bruce Willis's wife in The Sixth Sense. One wonders how much longer she can enjoy such self-imposed obscurity with so much work in the pipeline.

She has just finished filming Peter Pan in Australia, directed by PJ Hogan (Muriel's Wedding) in which she plays Mrs Darling. Then in May she'll be starring alongside Tim Roth, Rupert Everett and Dougray Scott in To Kill A King, an English Civil War drama. You'll also see her in The Heart of Me starring Paul Bettany and fellow South Hampstead girl Helena Bonham Carter.

'Working with Helena was amazing,' she says. 'At school she was the girl in the year above whom I worshipped from afar. I watched her play Celia in As You Like It and remember her writing poetry for the school magazine. And now I get the chance to play her elder sister. We got on really well on set and are now good "virtual" friends, e-mailing each other regularly.'

We are talking in Olivia's flat in Marylebone, beautifully decorated with dark oak floors and dusky colour-washed walls. She moved here last year, finally making the break from the Camden family home she shared with her parents for the past 33 years. 'It was a very secure environment. I had a little flat at the end of their garden.' Even though she's left home, she still refuses to move to LA and says she much prefers local restaurants and a bottle of wine with friends to The Ivy and Soho House.

Certainly she seems more relaxed in an informal setting; she sits cross-legged in her fake Juicy Couture tracksuit ('ten quid from Portobello') next to a roaring fire, drinking red wine and devouring a plate of cheese and biscuits.

The only drawback is that such a busy working schedule means she can't spend as long as she'd like relaxing in her new home. 'Nobody tells you that when you become an actor you will probably never spend more than three nights in the same bed,' she says. 'Being cast in Peter Pan, I found it quite hard accepting the part of a mum whose children are 13 and seven! It made me feel a bit panicky. I have only been in long-term relationships and I assumed all of them would end in marriage.'

Her relationship with actor Jonathan Cake, who played Sir Oswald Mosley in the Channel 4 drama, ended dramatically five years ago. They met at Cambridge and Jonathan proposed after seven years of being together but then, just two weeks before the wedding, he backed out.

According to newspaper reports at the time, he started dating Jemma Redgrave soon after their break-up, while he was filming Mosley. Olivia was devastated, naturally, but is now philosophic about the break-up: 'We were an extremely successful couple for however many years but the person you pick out as a boyfriend at 21 may not be right as your life partner. I think it's a good thing that we're not married to each other now.'

A transatlantic two-year romance followed with Canadian novelist Peter McCormack, but that faltered, too. 'Women don't know when the time comes in a relationship to say, "Get lost unless you want kids," whereas the men are happy to just trundle along and see no hurry to reproduce.'

Now Olivia is in the early stages of a relationship with a fellow actor, Rhashan Stone, 33, from TV hospital drama Holby City. Originally from Harlem, he moved to England as a child.

The couple have been friends for the past eight years after meeting through fellow actors but only started dating in the last few months. He recently earned the nickname 'Snakehips', after some saucy dancing with Olivia at the recent Evening Standard British Film Awards party. 'Everyone knows him for being on Holby City but he is an amazing Shakespearean actor,' she says proudly. 'And an extraordinary musician.

When he sings in the shower every day, it's like having Stevie Wonder in your bathroom.' Friends say they have never seen her look so happy. 'It is a great relationship and we are having a lovely time,' she agrees. 'Yet since we started going out I have already spent most of the time away filming.'

She admits: 'I do feel an age pressure on me as far as children go. I really want to have them and would never put my career before this. And I have never assumed conceiving would be easy. I am becoming more aware of how many of my friends have had to use IVF or have had problems and it alarms me enormously. The biological clock is ticking.'

The younger of two daughters (her sister Sophie is a lawyer living in Guildford) of two London QCs, Olivia, 35, was educated at South Hampstead High School for Girls and then read English at Newnham College, Cambridge.

Her acting skills were nurtured at Bristol Old Vic Theatre School. She was never convinced she would make a career out of acting but saw it as something that she would try before following her parents into law.

She began serving her time in rep theatre at Westcliff-on-Sea, doing work for the RSC and eliciting a rave review for a TV role as Jane Fairfax in Emma. But after a grim six-month period of unemployment, she was on the verge of giving up. Her big break came in 1997 when Kevin Costner plucked her, at the age of 29, to star in his $90-million uber-flop The Postman. Olivia did a video audition and Costner asked her to do another one because he didn't like her accent. In typical Olivia fashion, she refused. 'I don't know what possessed me but I thought whatever caught his eye last time, I'm bound not to do it again.'

But he liked what he'd seen so much, he insisted she fly to LA, which she did. Costner, who described her as 'one of the most beautiful women to come on screen in the last ten years', gave her the role - but the film was a turkey.

Somehow Olivia managed to escape unscathed and her second film, the excellent but underrated comedy Rushmore with Bill Murray, was hailed by critics as her real debut. It led on to the supernatural thriller The Sixth Sense - still the 15th biggest box-office smash of all time, raking in almost a million dollars. Since then she has rolled out a succession of movies including The Body, with Antonio Banderas; The Man from Elysian Fields, with Andy Garcia; and a collection of Brit flicks: Dead Babies, David Kane's Born Romantic and Lucky Break, by The Full Monty director Peter Cattaneo.

If her name isn't up there in lights like Bonham Carter's, Rachel Weisz's and Minnie Driver's, it is, she says, down to her refusal to play the Hollywood game. 'I like to do the negotiations myself and handle my own publicity. Why pay somebody else to do it?'

Almost all actresses affect a certain amount of contempt for publicity; it doesn't do to confess that, actually, you adore the paparazzi's fickle gaze. In Olivia's case, however, her disapproval seems authentic. 'I will only go to an event if I am in some way connected or interested.

If publicity is too important to you, it is completely soul-destroying if you make all that effort and the paparazzi turn the other way. When that happened to me, I just found it funny. I really do prefer going to an art exhibition than ending up face-down in a gutter in Soho, and that is my choice.'

It is also her choice to reject the casting-couch route to fame. 'I have been in a situation where I was literally being chased around the sofa and asked to get down on my knees by a studio boss. I suppose it is flattering to be offered the opportunity to sleep your way to the top, and be able to refuse it. It comes down to how much you want a job and my answer is always not that much.'

Certainly she doesn't seem remotely galled that she failed to get the Bond Girl part in Die Another Day. 'I got to the second auditions,' she says cheerfully. 'But then I asked for too much money. They expected me to do it for a third of my fee.' The part went to Rosamund Pike instead.

She's far more excited by her latest project with the National Theatre; Olivia is playing the Princess of France with Joseph Fiennes in Shakespeare's Love's Labour's Lost, Trevor Nunn's last production as director of the National, which opens today. Olivia swears she is not just following the trend of other Hollywood stars - stepping on to the stage for a pittance then retreating to LA with increased artistic kudos.

'I played the part at university and that was the last time I played a Shakespearean role. Now, ten years on, I am playing it again for the National,' she says. So much for those critics who scathingly described her career as 'going backwards'. She laughs. 'Yes. I started my career in Hollywood on $130,000 and have been working my way down ever since.' Really, though, it is Olivia's year, and she knows it. 'My career is not going backwards. I am now where I always wanted to be.'

Love's Labour's Lost opens tonight at the Olivier Theatre at the National (020 7452 3000)