"You'd think we were doing that Scottish play," Woody Harrelson sighs, his piercing blue eyes widening in mock horror at the thought of a cursed play. He could be forgiven for thinking so. His latest project, playing the lead in Tennessee Williams's The Night of the Iguana in the West End, has been dogged by off-stage dramas, including a flu-ridden leading lady and maintenance problems at the Lyric, which have resulted in previews opening six days behind schedule.
"I was losing my frickin' mind over the last week, just thinking, 'This thing is going to be a travesty,' " he groans. "I finally started to believe on Saturday that this thing could turn out good."
When we meet, on a chilly morning after a preview of the play, Harrelson looks tired, the fine lines on his face and white hairs in his beard making him look rather closer to his 44 years than his relaxed, tanned face usually suggests.
Was he tempted to throw in the towel? "I guess if someone would have told me before, 'You could just walk away from this', I might have," he says, with a rueful laugh. "It's hardly in my nature to walk away from something. In Chinese astrology, I'm an ox. I may be slow, but I'm steady and I just keep going."
Harrelson may have a lugubrious Texan drawl and reputation for playing "slow and steady" characters, but his self-diagnosis hardly does his career justice. He discovered his skill for acting at college in Indiana and performed in 26 productions there. He then set off to New York as a result of a bet, promising he would move to the Big Apple if his friend Clint was accepted at the prestigious Juilliard performing-arts school.
When Clint won a coveted place, Harrelson odd-jobbed his way around the city. He worked as a waiter, as a cook ("serving bacon and eggs at 4am on Columbus Avenue"), in construction ("taking asbestos out of a burnt building, wearing a flimsy little mask. God knows, I'll probably be dead in five years") and as "a temp who got fired from time to time", faking a typing qualification with a test certificate he found in a dustbin.
His first proper job was as an understudy in Neil Simon's Biloxi Blues on Broadway. Within months, he was behind the bar in Cheers, playing Woody, the dim-witted but big-hearted bartender, and soon everybody knew his name. Movie stardom beckoned and roles in some of the best-known films of the Nineties - White Men Can't Jump, Indecent Proposal, Natural Born Killers and The People vs Larry Flynt, for which he was nominated for an Oscar in 1996.
The past 10 years have seen a return to his theatrical roots, in The Rainmaker on Broadway and in The Late Henry Moss with Nick Nolte and Sean Penn in San Francisco. This is his second time treading the London boards - in 2002 he starred in On an Average Day at the Comedy Theatre alongside Kyle MacLachlan.
Harrelson describes The Night of the Iguana as "an epic poem that came from the soul of Tennessee Williams". Written in 1961, the play centres on the residents of a Mexican hotel, including Maxine, the predatory, newly widowed hotelier (played by Clare Higgins), Miss Fellowes, a devout Baptist (Nichola McAuliffe) and Hannah Jelkes, an artistic spinster (Jenny Seagrove). In the midst of this formidable trio is Harrelson as the Reverend Shannon, a defrocked-minister-turned-tour-guide with a penchant for heavy drinking and young girls, who brings a busload of Baptist students to the hotel.
It has not been an easy role to master: "I've grappled with it mentally," he says, putting his head in his hands. There are echoes of Shannon in his biography. Harrelson had a religious upbringing in Texas and Ohio and went to college on a Presbyterian scholarship. There, he "got hip to how man-made the Bible was" and turned to acting, gaining the reputation of Hollywood hellraiser for his partying, womanising and marijuana use along the way.
"I feel like I am Shannon right now," Harrelson says. "I don't know if it's the best place to be because he's on the verge of a crack-up." Harrelson's faith stays with him, albeit in an altered form: "I don't go to church, I don't believe that Jesus is my Lord and Saviour. I believe that Jesus was a great teacher, as was Gandhi, as was Mohamed, as was Buddha [he pronounces it with a drawl - Boo-dah]. My thinking and philosophy is closer, if I were religious, to Buddhism. But I'm still formed by Christianity. I still have more than bite-sized guilt."
These days, he preaches "the gospel of good diet, good ecology and nature". He lives with his wife, Laura (his former PA), and their two daughters, Deni and Zoe, in a solar-powered community in Hawaii. "We farm organically, biodynamically. Fruit trees, coconut trees, cacao trees. My big dream is to be able to say one day that I live on a chocolate farm." He grins goofily. "I am a hippie; a hairless hippie, but still a hippie at heart."
His stand on ecology has landed him in trouble with the law several times - for planting industrial hemp seeds to demonstrate their sustainability as a crop for making clothes and paper, for withholding his taxes, "as a protest against the way this government does business", and for demonstrating against logging on the Golden Gate Bridge.
Unsurprisingly, he has no time for Bush and his "greasy little cabinet". He says: "I'm really disappointed that Al Gore didn't get in there. Well, he did. He won the election, of course... For all his reported faults, in terms of being kinda robotic, this guy was a real believer in ecology."
Blair's backpedalling over Kyoto also comes under fire: "He's a frickin' puppet. The same way Bush is a puppet." A website (www.voiceyourself.com), set up with his wife, is the latest arena for his opinions. "I'm a big believer in the maxim, 'To whom much is given, much is required,'" he says. "Certainly I'll be able to look my grandchildren in the eye and say, 'I tried.' I don't want them living in a little man-made biosphere."
He apologises several times for "going off on a diatribe", but ecological issues clearly inform every area of his life, even when he is away from home in London. His baggy trousers are made from hemp, and he arrives at the hotel on his newest toy - a Brompton fold-up bicycle. (Although this new mode of transport may also have something to do with his altercation with a cabbie and subsequent arrest on his last visit to the capital.)
He shops for organic food at Fresh and Wild and enjoys reading The Independent: "You open papers and they have whole chapters of what's hot or not and not a frickin' page about what's going on ecologically. The Independent is an exception. It's like we're all sitting on the Titanic, clinking glasses and having a merry old time, yet the ship's already sinking."
He has settled into a temporary home near Marble Arch with his family, enrolling his daughters in school and playing football in Regent's Park every Sunday. He recently went to see James Nesbitt (whom he met on the set of Michael Winterbottom's Welcome to Sarajevo) in Shoot the Crow at the Trafalgar Studios ("Phenomenal... my kids freaked, they loved it so much.").
It all sounds very wholesome for Harrelson, the one-time party animal. "I haven't really gone nuts... If the play gets up to the point where it's easy to do - right now I can't even imagine that - I might start to [he adopts a theatrical tone] fall prey to my vices - the staying-up-late thing. I love hanging with people, and having endless conversations..."
I suggest that he is the kind of guy many people can imagine hanging with, probably as a result of the role that made his name - Woody in Cheers. At the first mention of the C-word, he is on edge. "I think we're going to do a reunion, get it going again... No. I'm kidding," he says sarcastically and starts to fiddle with his Blackberry, muttering "goddammit" under his breath. "It's my one major concession to technology. I'll never have a cellphone because they radiate your brain," he explains.
Returning to Cheers, he summarises, "It was pervasive. A lot of people saw it for a long time, so people probably do associate me with it, which is not so bad. I loved the character. It is a version of me - the most innocent part of me."
Natural Born Killers and The People vs Larry Flynt, which both caused ructions in his home country, were attempts to move away from Woody. "I was bothered by this narrow perception of me. I wanted to show that I could do something different. And then, it was ironic, when the movie came out, there were no big questions about whether I pulled the role off or not. No, the issue was 'this movie's violent'."
The past few years have seen him in more comic, whimsical roles. He has recently finished filming A Prairie Home Companion, written by Garrison Keillor and directed by Robert Altman. He agrees that comedy is his natural mode, joking about his latest role: "I said to myself, 'What am I doing in this play? It's so dramatic.' You just want to make people laugh sometimes. I'm not looking for credibility. Respect would kill me!" He laughs noisily.
Would he ever turn his back on acting, to pursue his campaigning full time? "No. I'm an entertainer. I'm supposed to make people laugh. That's what I'm supposed to do as a person," he muses. "Selfishly, the most pleasure I can have is to be on stage in a good play that the audience is digging. That's my deal, man."
'The Night of the Iguana', Lyric Theatre, London W1 (0870 890 1107) to 25 March