Welcome to Woody World

As soon as Woody Harrelson steps out of a taxi, sporting a cartoonish black eye, you think: Oh no, not again! It's only a few weeks since Woody made headlines after a late-night altercation with a London cabbie - headlines such as 'Movie Wildman Harrelson Flees 14 Cops At 2am'. But it's all right. The black eye turns out not to be the result of more cab rage but a stray elbow from his buddy Shane during a game of football in Regent's Park. That's 'soccer' by the way. Woody recently became a fan of our national game and now loves it so much he has installed his own pitch - 'a big oval soccer field' - at his hillside home in Hawaii.

He's rather apologetic about the taxi incident, for which he has since paid some 'nominal' compensation to the cabbie for a damaged ashtray and door, and he's happy to put his side of the story. But first, immediately living up to his kooky New Age image, he wants to move my mobile phone further away in case he is harmed by its dangerous emissions. 'I know for a fact the damage they cause,' explains Woody, gingerly handling the device. 'If I talk on this for three minutes my brain is screaming in agony. I'm real sensitive to these things.' Right now, he adds, cigarette smoke and second-hand cigarette smoke are the biggest causes of death, through heart disease and cancer. 'Ten years from now - cellphones and secondhand cellphones. That's my prediction.' I'm pretty sure he's being serious.

The cab story goes on and on - very entertainingly - but the gist is that it began as a 'little accident' when Woody couldn't open the ashtray to throw away a bit of paper and it eventually came off in his hands. The cabbie shouted at him, he shouted back, Woody asked him to stop the cab but he drove on while making a call on his mobile. At this point Woody decided to get out but discovered there was a 'design flaw' that prevented the doors from opening from inside. 'So I overcame that design flaw' - he smiles slightly - 'and then I got out, slammed the door and wanted to get away but he started following me. And then began the chase part, which is also pretty interesting!'

We pause while Woody gazes in childlike wonder at my notes ('What is that? That's shorthand! Oh my god, I've never seen that, that's what it looks like?') before resuming the story of the chase. 'He's kinda driving after me and then I'm running back at him and he's putting it in reverse and going backwards, talking on his cellphone all the time, and then he's driving after me and after about five 100-yard dashes I realise: Hey, I'm an idiot! What am I doing?' So Woody jumped into another taxi but was followed and caught at a traffic light, just as the police arrived. 'And then I started running and that was the really good chase part of the whole thing. And eventually they caught me and the cops were total gentlemen about the whole thing. They thought I was a bit of a maniac because I was yelling, "This is about an ashtray!?"'

The cabbie's dramatic story about 14 cops wrestling him to the ground was, says Woody, fanciful, but he did spend the next few hours in a police cell. And it was only a fortnight ago that charges were dropped. 'It's funny now but at the time it wasn't.'

Before meeting him, you think Woodrow Tracy Harrelson, 41, can't possibly be like Woody Boyd, the idiot savant barman from Cheers, but when you do, you realise Woody's most lovable attribute - the childlike naivety - is real. It's what fuels an idealistic and well-informed world view that encompasses a host of environmental causes ranging from legalising marijuana and promoting industrial hemp, to a vegan lifestyle (for himself and his children) and saving forests.

He used to have a bar in LA that served raw food and pure oxygen but it closed down. 'Asphyxiated,' he chuckles. 'I'm never going back into the restaurant business.' He's delighted with the decision to downgrade cannabis in the UK and believes sugar is the most pervasive drug in the world, followed by caffeine, not to mention tobacco, alcohol and prescription drugs. He's no puritan - everybody needs a drug of choice, he says, and cannabis 'is the best drug'. He lives with his wife and two young children in Hawaii, with a holiday ranch in Costa Rica, because of 'the surfing, the produce, the people, the weather - I love the tropics. To me it's beautiful. I love the greenery and it's great for my kids. Maybe I'm a dreamer but I just believe in this thing that your neighbours look after you and your kids, and they take care of you, and they care what's happening to you. I believe in this - a community that cares for each other.' And surely we all want that for our families.

Right now Woody is in London rehearsing for his West End stage debut in On An Average Day, a two-hander comedy drama with Kyle MacLachlan, by new American writer John Kovenbach. Woody had three films lined up when he read the script and he shelved them all. 'When I read this play everything went by the wayside. The impact was huge - it's one of the most powerful plays I've ever read. I love it. This is a dream come true for me. When that curtain goes up it will be a real exciting day.'

Woody plays a man reunited with his long-lost brother after their father left home when he was seven. Woody's own father left him when he was seven, too. A killer (who, according to Woody, worked for the CIA - 'I know who trained him'), Charles Harrelson is currently serving a life sentence for murder. Woody has long campaigned for a retrial, on the grounds his father was given inadequate legal representation, and expects to hear the answer in the next two months. He says he is 'not holding out an immense amount of hope' but believes that, if he is granted a retrial, he will be acquitted. What would that mean to Woody? 'Well it would be a big deal. I don't want a lot - I just want to be able to sit down and drink a beer with him, and not have a phone and thick glass between us, never be able to shake his hand and give him a hug.' Can he remember doing that before his dad left home? 'Yeah.' He looks away and clears his throat.

After that, Woody's strictly religious mother moved them away from Texas. 'I was very religious and went to church regularly, went to Sunday school, had Bible study in my house, went to college on a Presbyterian scholarship. I was in deep.' What changed his mind about studying theology was when he went to Hanover College, Indiana ('I started to realise exactly how man-made the Bible was') and living with a church minister ('I saw a lot of hyprocrisy and realised the church is a control mechanism').