Liam talks about sex

It seems entirely appropriate that Liam Neeson should be cast as pioneering sex researcher Alfred Kinsey. After all, the 6ft 4in Irishman spent his early years in Hollywood conducting his own study of the female form. Something of a Lothario, Neeson had a little black book boasting numbers belonging to Julia Roberts, Barbra Streisand, Sinead O'Connor, Brooke Shields, Jessica Lange, Cher and Diane Keaton - the last three were all co-stars of his. As Kinsey's 'Let's talk about sex' tagline hints, Neeson should be an expert.

Our meeting is scheduled to take place on a vertigo-inducing floor of a Los Angeles hotel, when the 52-year-old actor arrives, he's a shadow of his former self, dressed in blue jeans, a navy jacket and a sky-blue shirt. The soft Ballymena lilt that has wooed so many is gone. Suffering from laryngitis, he is reduced to speaking with a croak. While most stars would automatically cancel a press tour at the slightest hint of a sniffle, Neeson cares too much about Kinsey to shirk his obligation. The role has already seen him nominated for a Golden Globe, and as his co-star Laura Linney (Oscar-nominated for her role as Kinsey's wife) notes, 'Not many people could pull off what Liam did in this.'

Whether it's playing Oskar Schindler for Steven Spielberg in Schindler's List, his only Oscar-nominated part to date, or the lead in Neil Jordan's IRA drama Michael Collins, Neeson is at his best when realising controversial true-life figures. He is currently in talks with Spielberg about playing US president Abraham Lincoln. As for Kinsey, Neeson has already seen his cultured turn criticised by right-wing Christian groups in the US for lionising a man whose 'proper place is with Nazi Dr Josef Mengele or your average Hollywood horror flick mad scientist', as Robert Knight, director of the Culture And Family Institute, stated.

As shown by the film, written and directed by Bill Condon, since the publication of Kinsey's revolutionary 1948 book Sexual Behaviour In The Human Male, he has been lambasted for encouraging everything from the homosexual activist movement to the introduction of pornography into the mainstream. 'We are living in a neo-conservative time,' says Neeson, a resident of the US since he moved to Hollywood in the late Eighties. 'Sex is a contentious issue. We have everything from over-population to sexual abuse to gender equality to HIV/Aids. These are sexual issues that are shaping the world. Kinsey was one of the first to analyse sexual health on a grand scale.'

In many ways, it's a role Neeson was born to play. As a teenager, after winning the Ulster Youth Boxing Championship three years in a row, Neeson studied physics, maths and geology at Queens University, Belfast, but left before graduating. He then went on to train at St Mary's Teaching College in Belfast. Again he left early, after being dispatched to Newcastle-Upon-Tyne to try his hand with students. 'I was terrible,' he laughs. 'I was sent out to do teaching practice in Geordieland, teaching 12- and 13-year-old girls maths, physics, and drama. They were terrifying. I couldn't control them.'

Raised as a Catholic in a largely Protestant area, it's little wonder the shyNeeson found it hard to express himself. It was as an amateur performer, chiefly for Dublin's Abbey Theatre, that he found his voice. Spotted by John Boorman, who cast him as Gawain in his 1981 film Excalibur, Neeson soon found himself living in London with his co-star Helen Mirren. A small role in The Mission got him further notices, winning him a bit-part in Miami Vice.

He went on to work with the likes of Sam Raimi (Darkman) and Woody Allen (Husbands And Wives), and these in turn led to Schindler's List. But Neeson never capitalised on that career high, preferring to return to the relative anonymity of the stage. 'I wouldn't like to be Leonardo DiCaprio or Tom Cruise,' he says. 'Not to be able to leave your front door would be very strange. I've seen it first hand, but I can't relate to it. People go "Are you - er?" and that's about it.' When he did try his hand at major league movies (The Phantom Menace, The Haunting, K19: The Widowmaker) they were all let-downs.

Not long after a near-fatal motorbike accident in 2000, Neeson proclaimed that he was no longer interested in Hollywood, but appears to have gone back on his word. This summer sees him star in two blockbusters: as the Caped Crusader's mentor in Christopher Nolan's Batman Begins, and as father to Orlando Bloom's warrior in Ridley Scott's Crusades epic Kingdom Of Heaven. Admitting he's 'had good and bad experiences with big films', Neeson was tempted by the chance to collaborate with some genuine auteurs. 'I'm not saying other directors are jaded, but these guys do have a freshness that's kind of wonderful.'

Having interviewed Neeson before, when I found him truculent and uncooperative, he now appears open and relaxed. If the one-time wild man of Hollywood has been tamed, we partly have his wife of 10 years, actress Natasha Richardson, to thank. They have been together since 1993, and theirs has been a solid marriage --to the point that they successfully sued two Fleet Street papers in 1998 for suggesting otherwise. Living with their two sons, nine-yearold Michael and seven-year-old Jack, on a huge ranch near the town of Millbrook outside New York, they lead a seemingly idyllic existence.

Given Kinsey's research into the male appetite for sex, as well as Neeson's own bachelor days, does he think monogamy is realistic? 'Oh, absolutely. It's not easy. But, yeah, I think so.' So what does sex mean to him now? 'I believe it defines you. I guess because I'm a father, it is a special thing. When I was a young boy, I was running around and trying to kiss girls - now it's something I do not treat lightly. But I'm blessed because I'm in an extraordinary marriage and have two amazing kids.'

Kinsey opens Fri 4 Mar.