THE pride and the passion with which Natasha Richardson talks about her latest role is as obvious as the looks and voice that clearly identify her as one of the Redgrave acting clan.

She refers to the movie in question, Asylum, as "a minor miracle", reflecting the seven long and often frustrating years she spent trying to bring Patrick McGrath's novel to the screen.

"It's bizarre really and I find myself getting a bit choked up when people say nice things about it. It does feel very weird to have worked on something so long and it finally seeing the light of day," she says

The actress daughter of Vanessa Redgrave wanted to play the role of Stella as soon as she read the book and simply wouldn't let go of the role. Stella's a wife and mother yearning for romantic love in 1950s England and finding it with one of her husband's violent, psychiatric patients, although their affair triggers off tragic events.

"I felt I really understood her, where she came from, her journey," says Richardson. "Not because I thought, 'I am this woman, this woman is like me'. Of course, there are elements we have in common - she's a hopeless romantic, so am I. There are women in my life who I think have elements of her, who've been through an unhappy marriage or alcoholism or breakdowns.

"Maybe it's all of those things, maybe none of those things. It's just a gut reaction. It's not often you feel a part has your name written on it and I had boundless determination to do it because I thought no-one else is going to give me this opportunity."

This sounds oddly like lack of confidence from an actress who's more than proved herself on stage and screen, with movies including Patty Hearst, The Comfort Of Strangers and A Month In The Country and her Tony Award-winning portrayal of Sally Bowles in a Broadway revival of Cabaret.

The journey of Asylum to the screen was a difficult one and along the way she lost her actor husband Liam Neeson as her co-star. The film would have been different with him as Edgar, the wife's lover, but "better, worse, I don't know", she says. "People come up with all these rules about chemistry between actors. Some say married people shouldn't work together because they have no chemistry as they are too comfortable with each other. I don't think that's true. You can have chemistry with someone you don't get on with at all, or chemistry with someone who's your best friend, or no chemistry at all with someone you're having a hot love affair with."

So the chance was lost to see if Neeson and Richardson have screen chemistry. There's no doubt that she and Marton Csokas, who was cast as Edgar, do sizzle on screen in heavy duty sex scenes that make you think of The Postman Always Rings Twice or Last Tango In Paris.

"They had to be very erotic, very hot, to see that uncontrollable desperate lust," she says. "What's in the film is the tip of the iceberg of what we shot. It's definitely Last Tango In Paris and beyond. Some scenes were easier to do than others. Some were quite carefully choreographed, others the director let the camera roll and wanted us to improvise.

"Exposing yourself in that way to the camera makes you very vulnerable as a woman, but the thing that's toughest is what it does to your head. It's a fine line between that and prostitution. You are pretending and convincing yourself almost, then someone says 'Cut' and you walk to the other side of the room. So it's a very inhuman, unnatural thing."

Losing Neeson must have been a disappointment, if only because his name would have helped raise the finance, but as Richardson points out Edgar wasn't the part of his dreams whereas Stella was her dream role. Ironically, he went off to film Kinsey, about the American sex researcher.

The similarity in sexual themes between that and Asylum aren't lost on her. She sees Asylum as very much a story of its time, the 1950s when middle class, upper class women were required to be a dutiful wife and nothing more. She had help to do the housework and a job was out of the question.

She'd still like to work with Neeson but has yet to find the right vehicle. They live with their two sons - Michael, ten, and Jack, eight - in New York, a home temporarily deserted to promote Asylum's opening in this country. It wasn't just work that took them there but a deliberate choice to live there.

"I'd fallen in love with the city and felt a sense of being able to be my own person," she says. "I suppose in a way I was getting away from the history and family baggage, the same reasons that draw a lot of people to New York to start a new life. It seemed to make sense. It was where Liam and I decided to start our life together."

Living in the US puts Richardson into a quandary over stage work in this country as it's hard for her to come over here when her sons are in school in New York. "I can do a short run of a play in London, which I would love to do because it's my home and my culture," she adds.

Richardson's determination to bring Asylum to the screen doesn't mark the start of a career as a producer, although people have told her she should consider it.

Richardson will next be seen in the Merchant-Ivory film The White Countess with her mother (playing her aunt) and her aunt, Lynn Redgrave (playing her mother-in-law). She last appeared with her mother on stage when she was 22. This time it was "a delicious treat to all be together".

Having got Stella out of her system, Richardson intends to take a break from playing "alcoholic, chain-smoking, crazy ladies". She's going to do nothing, planning to take a break for the rest of the year after filming in China and starring in a revival of Tennesse Williams' A Streetcar Named Desire on Broadway.

"I want to make my sons my priority for the next few months," she says. "Stella in Asylum was a part-time job for so many years. I need to take a breather, although I find normal life much harder than work, just dealing with family life, school or whatever. It never feels like putting your feet up."

Because filming Asylum was so fraught with problems, the cast kept up their spirits by having a lot of laughs. Richardson pays tribute to co-star Ian McKellen and Hugh Bonneville for helping her through the difficult times.

"They kept me going," she says. "It was so intense and we were under a lot of pressure timewise and financially. Every week we didn't know if there would be money to carry on. We even stopped filming at one point but the backers came back. We'd got so far. I thought my heart was going to break."

l Asylum (15) opens in cinemas tomorrow.

l See film review on page 10 of today's 7Days