It's 11am and Ian Hart is hungry. Evidently so. He attacks his croissant in much the same way as he acts and talks - with an alarming intensity. Sitting still for half an hour clearly doesn't come easily to him. "I need something to do when I'm not working, or I crawl up the walls," he explains. "So I've just taken up kung fu. I was looking for some kind of calming, relaxing activity. I tried yoga, but it wasn't really me."
It's this twitchy, aggressive hyperactivity that made Hart ideal to play the Beirut hostage Brian Keenan in Blind Flight - a recreation of the former teacher's five-year imprisonment, alongside John McCarthy, at the hands of Muslim fundamentalist militiamen.
Hart is no stranger to playing real people - he has been cast as Beethoven, Joe O'Reilly in Michael Collins, and John Lennon (twice). But Blind Flight was the first time he actually met the person that he was about to portray. "I made the mistake of reading Brian's book before I went to meet him," he says, dabbing at the flaky debris of his breakfast with the tip of his finger. "And it totally prejudiced my view. You read the book and think, 'This guy is incredible'.
"The way I see it, the torture Keenan and McCarthy went through, and came out the other side of, was epic - like Homer. Massively heroic. How can you portray that as an actor? It's one thing standing up to guards - telling them to fuck off even though they're holding a Kalashnikov - when you know you're going to survive. But Keenan never knew that. You can never say, 'I know what you mean', to him. No, you don't."
Hart and his co-star Linus Roache (who plays McCarthy) fasted for three months in preparation for the 32-day shoot, to achieve the necessary emaciated look. They both lost around 30lb, dropping to around nine stone, and filming most of their scenes in a freezing warehouse in Glasgow, wearing only skimpy shorts and vests, while pretending to be suffering extreme Middle Eastern heat. "Starving myself bugged the life out of me" Hart confesses. "When you're hungry and cold you get snappy, you get pissed off - everyone does."
Did he ever lose his rag on set? "Every bleedin' day. And it's pathetic. I mean, all you're doing is pretending you're suffering. You're not really suffering. You can go home any time you like. So it's inappropriate to behave like that. Still, losing all that weight really does mess up your metabolism up. After we finished filming I put on a stone in less than a week. That's not normal."
I first interviewed Ian Hart a year ago, a few weeks before he set off to start filming Blind Flight. When I asked him what he hoped 2003 would bring professionally, he announced: "I just want to be rich and famous." This seemed rather a bizarre statement from someone who had already appeared in over 40 films (the tally will be closer to 50 by the end of 2004), but in a sense you can see his point. Among his thespian peers, the Liverpudlian actor may be considered one of the finest talents of his generation, and yet the general public's response when you mention his name tends to be at best, "Doesn't he play for Leeds?". At worst, "Ian who?".
Even if you don't know Ian Hart's work, you probably have the feeling that you've seen him before. And you surely have. Apart from some best-forgotten stinkers (Killing Me Softly, The Closer You Get), his acting CV reads like a roll-call of quality Brit movies: Land and Freedom, The Butcher Boy, Michael Collins, and a comic turn in the luvvie-laden Born Romantic. He was briefly in EastEnders, and, in 2001, played the stuttering Professor Quirrell in Harry Potter and the Philosopher's Stone.
Surely the offers from Hollywood came flooding in? "Nah," he says, removing his baseball cap and violently rubbing the top of his shaved head like someone polishing a shoe. "Harry Potter made absolutely zero difference. I never got a job off the back of it." All the same, he's chuffed about contributing to a franchise that will doubtless become an international institution in children's entertainment: "It'll be on at Christmas and Easter for the next 25 years. It's like being in Chitty Chitty Bang Bang."
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Now a youthful 39, Hart is aware that his career has been, in a sense, waiting to kick off for the past 10 years - ever since his intense portrayal of John Lennon in Iain Softley's Backbeat had him dubbed The Next Big Thing. "If I'd have gone out every night of the week from Backbeat onwards, and had my picture taken with pretty girls," he says, breaking into a comic rant, "I'd be much more famous by now. What do we assess fame by - going out with one of the Appletons?
"My philosophy was, if I just do good work, someone will like it enough to employ me. But that wasn't enough. It never made me famous. And I'm way, way too old now, mate. That boat's sailed. It's about halfway across the Atlantic by now."
Warming to the subject, now he really puts his foot on the verbal accelerator: "To be honest, I don't know how to construct a career that'll make me famous. Except maybe get my ears pinned back, get my teeth done, get a syrup [wig] and go to America. But then I'll be competing with billions of actors who haven't got false teeth, and who are 25, not pretending to be 25."
He comes up for air. Surely, I counter, being a huge star has its downsides? With fame would surely come increased attention, some of it negative. "You're right," he says. "I get none of that. Nor would I cope with it particularly well. I'd be Liam Gallagher. I'd be chinning journalists galore. I don't even cope with driving to Ikea without getting into a nark. So maybe it's for the best. But a little bit more attention wouldn't go amiss - just because it helps you to get better parts."
As you may have guessed, Ian Hart is an interviewer's dream. This is for two reasons. Firstly, he's likeable and furiously bright (how many actors name-check Chomsky in interviews?). Secondly... he's an absolute nutter. And I mean that in the nicest way possible.
It's not just the constant motion - the twitching, the head-rubbing, the manic gum-chewing. Nor is it the hyperactive Liverpudlian verbosity. No, it's the fact that, in the sea of polite banality that is the typical celebrity interview, Hart is like a marauding U-boat. He will happily gob off about anything you ask him to.
Not even Hart's acting idols are safe. When I compare his Blind Flight weight-loss to Robert De Niro's legendary Raging Bull bloat-up, he retorts: "Yeah, but De Niro had six months to do it and a personal trainer. I love De Niro, but with the same kind of team behind you, you'd get the same result. I'm not saying what he did wasn't amazing, but it's like the way everyone seems to think Daniel Day-Lewis invented acting just because he stays in character for a while."
Hart's background alone sets him apart from your average actor. He grew up on a council estate in Liverpool (his father worked at the Ford factory at Halewood, his mother washed dishes part-time in a school kitchen). Young Ian attended a Catholic all-boys grammar school, where he got a reputation among the nuns for being argumentative (no surprise there).
His first taste of acting came with a part in the 1983 TV series, One Summer, a seminal tale of Scouse tearaways going wild in the country. It took over a decade for Hart to make any money from acting, however. Indeed, when he first moved to London in 1983 to attend Mountview Drama School, he ended up sleeping rough. He didn't have the money to get a flat, and when he rang about rooms, people would ask if he was Irish and put the phone down. After two months, he dropped out of Mountview and returned to Liverpool. During the lean years to follow, he worked at a factory, a farm and the Post Office. Success only came in 1994, with Backbeat.
Hart has been with his wife Lynne, a teacher, for 14 years, and their daughters, Daisy and Holly, are seven and three respectively. Ironically, recalling our earlier conversation, he concedes that becoming "rich and famous" would come with a heavy price-tag. "I'd have to leave behind my wife and kids and spend a year in the States, and that would be hard, maybe too hard."
Perhaps Ian Hart's problem is that he's a bit too honest to be in the fame game ("Not honest," he says, "stupid"). None the less, he continues to bag quality parts and work with the cream of cinema from both sides of the Atlantic, such as sharing a few scenes with Johnny Depp in the forthcoming JM Barrie's Neverland. "It's a tiny part," shrugs Hart. "I'm basically there so that Depp has someone to speak to. Otherwise, the film's a monologue. But I knew it was only a couple of days work, and I figured I'd learn more doing that than sitting at home."
Next up are Sydney Pollack's The Interpreter - with Sean Penn and Nicole Kidman ("I just hand some papers to Penn") and White on White, the third in a trio of adaptations based around Patricia Highsmith's Ripley character. Generally, Hart's feeling positive: "I just wanna build momentum again," he says. "Keeping yourself in work is one thing, keeping yourself in good work's another. But if it doesn't work out, so be it. As the Taoists say, 'Learn to accept that which you cannot change'."
But doesn't he feel bitter? Or unlucky? "Not at all," he says with typical passion. "I'm still working, I've got two arms, two legs, two gorgeous kids, a lovely wife. Fifteen years ago, I was homeless. So when you think about it, I'm lucky."
'Blind Flight' is released 9 April
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