How did he get here?

Patrick Stewart looks slightly bewildered. It's as if his most famous alter-ego, Captain Jean Luc Picard of the starship Enterprise, has been beamed down from the transporter room to the wrong planet. "The whole thing still has a deep air of unreality," he muses about his unexpected career as a sci-fi superhero. "Even just sitting here talking to you about it. I know what happened, I know that by a fluke I was seen and got offered this job in Star Trek. But now so many years have passed, and I still have a slight sense that I'm going to wake up and find I've got a call at 10 o'clock in the Barbican for a rehearsal. It's not what I wanted as an actor. It's not what I was working towards. It's not what I expected."

In 1987, Yorkshire-born Stewart, a stalwart of the RSC and the Young Vic, with occasional TV roles to his credit, was in the middle of a solidly respectable career on the British stage. But following a literary reading given by the actor, a long-time associate of Star Trek creator Gene Roddenberry recommended Stewart for a role in the new series, Star Trek: The Next Generation. Knowing next to nothing about the original series, Stewart arrived in Los Angeles expecting a supporting role as the "token Englishman". He was so sure his character would soon be dropped that he didn't bother unpacking his suitcase for six weeks.

By the time the hit show finally came to an end seven years later, Stewart was one of the most famous faces on American TV. Three lucrative Star Trek movies have followed, along with roles in blockbuster movies such as the Mel Gibson vehicle, Conspiracy Theory. Now he's starring in one of the year's biggest hits, X-Men, based on the long-running comic strip by veteran Stan Lee.

"It's yet another unlooked-for event in my career," he says. "I actually resisted X- Men quite firmly for some time. It was meeting (director) Brian Singer and talking to him about the project that persuaded me that this stood a chance of being something more than another tongue-in-cheek comic-strip movie. I really wasn't interested in the sort of tone set in Batman or Superman. And, having been associated with one long-running franchise, I was reluctant to get involved in another one."

There's no doubt, then, that X-Men is going to run and run? He laughs heartily. "You'd better believe it. All of us in the movie are committed to a two-picture deal. That was actually a deal-breaker if we didn't agree to it. There's no doubt at all that there'll be an X-Men 2. That caused me a lot of concern - it really did. Because for the last few years I have been trying to swim against the tide of Next Generation, insofar as it gave me a commercial status I'd never had before, but it stamped me with the identity of a particular kind of character and a particular kind of show. For the most part it's not been a handicap, but now and again it is, and that's frustrating."

It was Singer's work on films such as The Usual Suspects and Apt Pupil which helped sway Stewart in considering the role of Xavier, the telepathic leader and teacher of a group of "mutants" with incredible, extrasensory powers. Feared and hated by those who cannot accept their differences, the mutants are outcasts from society, their similarities to other oppressed minorities made explicit by the film. "Brian was determined to make a serious movie," says Stewart. "I was already a fan of his work, and that's what made a difference, and also why the film has found a very broad audience, I think."

He agrees that people tend not to take science fiction, especially on film or television, very seriously. "It's been a 12-year battle for me, as far as Star Trek is concerned. I think it's particularly hard in the UK to persuade people that there is something of substance to this work. We actually spent seven years, through 178 episodes, of bringing substance to it. But people believe it's trivial and escapist. That was a battle we had to fight all the time with Next Generation. The difference here is that X-Men is set in a very recognisable present day, and the character I play is a contemporary individual. It's just that he's surrounded by these extraordinary individuals. Had it been futuristic in any sense I couldn't possibly have taken it on."

X-Men sees Stewart reunited with an old RSC colleague, Ian McKellen, who plays his arch-adversary and former friend, Magneto. "It was fun, because I'd only recently reconnected with Ian after years of not seeing much of him," Stewart says. "He came to Los Angeles with a National Theatre production, and very soon after that his name was linked with X-Men. It's not an accident that Brian brought us together, although he wasn't aware that we're both Northerners with similar backgrounds, attracted to the same kind of theatre. It does give substance to what is the central relationship of the X- Men stories. I just hope that if there are to be more movies we shall spend more screen time together."

Growing up in a working-class Yorkshire family, in what he has previously described as "a very poor and very violent household" (his mother was a weaver, his father a former soldier "who had numerous jobs"), the prospect of becoming an actor seemed very remote. "I went to a secondary modern school, and I didn't know anybody who had become a professional actor," he says. "But on the other hand, I came from a community where to be a performer was not unusual. My town had a population of 11,000 people and at the time I left for drama school, I counted 11 fully functioning amateur drama societies in that town alone. Some of them might have only done one play a year, some did three or four, but to be a performer was not unusual."

I wonder what drives him now, having just turned 60. After all, from a relatively early age - perhaps because of his baldness - he has been playing authority figures of one sort or another. "I know, I know," he sighs. "I even have a one-man show I've created around these figures. A psychologist would probably say that it was an attempt to get as close as possible to my father, who was a big, powerful, authoritarian figure." The evening before we met, he mentions, he was in Madame Tussaud's for the unveiling of his own waxwork effigy. "As I walked around it I had the rather unnerving feeling that I was walking around my father. If you'd stuck a moustache on it, there would have been Alfred Stewart."

He agrees with Liam Neeson's statement last year, after working on Star Wars, that the process of working on special-effects movies does not exactly demand much in the way of acting. "No, of course not. You're probably working at about 5 per cent of what you can do as an actor. It's extremely technical and really only requires that you're in the right place. It's not intellectually or emotionally challenging at all. I very quickly got bored with that side of things. As it happens, in X-Men my character never gets close to the action, which is fine by me, because I've reached an age where I don't really want to be having things thrown at me. I've done quite a lot of that and I'm looking for a quieter life in front of the camera."

He expects to be spending much more of the next decade in theatre, he says. "I made that decision about a year ago. I was very restless, and I asked myself what makes me happy. To be honest, I'm happier in a rehearsal room or on stage. I love filming, I'm fascinated by it and the rewards are terrific. But this is probably partly because I don't get the film roles - and there are only a handful that are truly challenging. How many extraordinary screenplays, like Being John Malkovich or American Beauty, do you see in the course of a year? There are only so many fascinating screenplays and roles going around, so you have to accept the fact, if you're working in film, that you're going to be doing mediocre work most of the time. I've reached the point where I don't have to do that, so I'm looking for that which makes me happy. I have an acute sense of time's winged chariot, and a lot of work has passed me by. I would be very discontented if I didn't play those roles - Lear, Macbeth, Falstaff."

Does that, I wonder, hint at some regret at spending most of the past 13 years in movies and TV? "Not a bit of it, because it's given me opportunities I wouldn't otherwise have had. I've just finished 18 weeks playing the lead in an Arthur Miller play (The Ride Down Mt Morgan) on Broadway. I would never have been in the running for that if it hadn't been for Star Trek."

As for Star Trek itself, he believes fans can expect to see the Next Generation crew taking the Enterprise out for one last voyage. "I have a 28-page storyline for the next one in my briefcase. It's very interesting - John Logan, who wrote Gladiator, is writing it. It's the first time they've brought in a non-Star Trek writer to develop a Star Trek feature. It's happened because he's a Trekkie, a fan who just happens to write screenplays on other subjects, but really wanted to do this." The best of the three movies, he agrees, is the second one, First Contact, which features the most intriguing and disturbing of Captain Picard's adversaries, the hive-like Borg. "Exactly, and the problem with the one we're doing now is that we've got to find something that matches the Borg, or is even better. We didn't manage that with the last one. But I think that will then pull down the curtain on The Next Generation; I'd be happy with that."

X-Men is on general release