Film: Missing: one brilliant career

Kerry Fox is a queer fish. On screen she can be pretty or pudding- faced, docile or dragonish. Off screen she's equally changeable. One minute the star of Shallow Grave and Welcome to Sarajevo is gushing happily about a favourite director, the next glaring stonily at you before snorting with laughter at some secret joke. A private, rather prickly person, she seems to delight in deflecting attention from herself by inhabiting a series of wildly different characters.

When the ambitious New Zealander began acting, her protean role-play ensured her a flattering, if rather frustrating anonymity. Watching the shy, ginger-haired frump in Jane Campion's brilliant Janet Frame biopic An Angel at My Table, the ANC activist in Friends, and the Home Counties lesbian who seduces repressed housewife Sophie Ward in ITV's dollop of Joanna Trollope, A Village Affair, few people realised it was the same person.

"People find me hard to pin down," agrees Fox with a sly smile - and that's just the way she likes it. She enjoys playing hard to get: soul- baring isn't her style, nor is fanfaring her new projects to the press. And she's not mad about reading for roles either, a peccadillo that nearly cost her her latest part. The actor had just returned from shooting Walk With Lions in Africa with Richard Harris when she heard about Fanny and Elvis, the debut feature from Band of Gold creator Kay Mellor.

"I was buzzy," she giggles, "Overexcited. Kenya was great. Amazing. Then I came down to earth with a bump. When I met Kay I was jet-lagged and couldn't concentrate. I just said, `I've had enough of this meeting, I'm off'.''

Fox promised she'd be back in a couple of days but when the day dawned for her audition she made her agent phone in and say she was sick. "That was Wednesday afternoon. On Wednesday night I went to the opening of a friend's play as her guest. The other guest was Kay." Before the curtain went up Fox hid behind a cloud of cigarette smoke but by the second break the game was up. "I was knocking back the drinks and Kay asked, `are you feeling better now?'" she laughs. "I said, `I'm really sorry, I lied, I just couldn't face it'."

Mellor must have recognised something of her flaky heroine in Fox, because the next day she offered her the role without a reading. Kerry became Kate, a thirty-something romantic novelist deafened by the tick-tock of her biological clock. When her lecturer husband runs off with an oversexed student, Kate sets off on an odyssey to find the future father of her child. One of the more unlikely sperm donors is wideboy second-hand car salesman Ray Winstone. The fear of infertility and postponed parenthood is one Fox feels is "in the air". At 33 years old the actor says she wants to have a baby but "in this business it's tricky. I'm terrified of not being able to work for that long."

Despite dipping its toes into such dilemmas, the film's knockabout tone is not so much test-tube tragedy as Woman Behaving Badly. Fox had a few problems with that. "Intellectually" she says, "I know that being cutting is what makes things amusing. But it's hard to trust that when you're in the rarefied atmosphere of the set. You want the immediate buzz of the joke, so you go over the top to get a laugh."

Her co-star Ray Winstone was "big, generous and warm. Neither of us had played a role like this before," she says, "so we both felt fragile." She goes silent. "I was just thinking about an interview I read in the Evening Standard where he said it was not the kind of film he would go and watch." The abrupt, almost belligerent, front falls away for a moment and she looks a little forlorn.

As a child growing up in a leafy suburb of Wellington, Fox was shy but also "an enormous show-off". She went to university but found it dull and dropped out, drifting slowly into acting. After An Angel at My Table she moved to Australia, where she shared an apartment with her sister on Bondi Beach. Her search for work was split between Britain and Hollywood until she landed the role in Shallow Grave and set up home in London with her husband Jaime and another couple.

So have things worked out for her here? Fox says she always chooses roles which let her "learn more about human nature". But recently her judgement seems to have gone a little wonky. The Wisdom of Crocodiles in which she appeared alongside modern-day vampire Jude Law sucked, while her return to the stage in a production of The Maids at the Donmar Warehouse received some stinking reviews (in retrospect Fox believes they "never really cracked the play. It was a very literary piece and I never felt on top of that"). "I don't know whether you can direct your career as an actor. There are certain ways of giving yourself the opportunity to become a star. But that's never really been my aim."

This year, she says, has been fantastic "because I've only done one job". Free time has been spent entertaining visiting friends and family. If she's not out doing "touristy things" she enjoys "pottering around the house doing yoga and drinking tea".

Of course with an actor like Fox, who has spent her life touring her talents around the world, it's only a matter of time before all this comfortable domesticity comes to an end. After walking with lions("they were flown in from Hollywood," she laughs), Fox feels ready to splash out on "a big-budget underwater action movie".

Swimming with sharks? "Maybe a little more surreal," she suggests. "Something with deep sea monsters."