A revealing afternoon with the Naked Rambler

In a brief moment between Stephen Gough's periods of incarceration, Matthew Bell stripped off and joined him for a stroll around Perthshire

For something so awful to contemplate, actually doing it was surprisingly easy. With a quick tug of the wrists, my boxers were off and tossed on to the pile of clothes, and I was naked by the side of the road. If there's one thing less sexy than standing white and wilted on the verge at noon, it's then putting back on your socks and boots, and trudging off down the road.

Still, I wasn't here to feel sexy. I was here to find out why Stephen Gough, aka the Naked Rambler, has dedicated the past nine years to one of the most bizarre and obstinate campaigns for freedom of expression since the first lemming hurled itself off a cliff. Since 2003, when the 53-year-old former Royal Marine embarked on a nude hike from Land's End to John O'Groat's, his life has followed a self-perpetuating cycle of arrest, release and arrest, all because he refuses to wear pants.

On Tuesday, he was released again from Her Majesty's Prison in Perth, this time after six years in solitary confinement. Yes, you read right. Six. Years. Admittedly, it wasn't all one sentence, but after the last two times he was released, he was re-arrested on the doorstep and sent back in. This time, he had made it as far as Duncrievie, a small village nine miles south of Perth, where I caught up with him to share the breeze.

We head for Hampshire, where his 85-year-old mother lives, though nobody pretends we'll actually get there. Tayside Police may have decided not to arrest him, hoping he will get out of their area, but Fife Constabulary will be another matter. So if he knows he'll be arrested, why keep doing it? "It's freedom, innit," he shrugs. "It's not about nakedness at all. Freedom has to be expressed somehow, and society is not allowing me to be as free as I want to be, and it doesn't make sense. So you start to rub, you start to push back the boundaries."

Walking unclothed isn't technically an offence, though clearly some people find the sight of a dangly dongle offensive. "As long as you're not hurting someone else, what's the harm?" Steve reasons. "Bodies aren't offensive. They're part of nature. Why don't people get offended with other bits of nature?"

As we stride towards the Lomond hills, the response from the public is overwhelmingly positive. Farmers grin, motorists hoot and one Lycra-swaddled cyclist yells: "Well done, Steve, keep it up!" During the four hours I spent scouring Perthshire beforehand to find him (he hasn't got a mobile, and sleeps in the woods), the reaction to my question "have you seen a naked rambler?" was invariably laughter. One woman purred: "Ooh, I'd love to." Only one matriarch barked: "He should put it away!" So what's weirder: this grizzled freedom warrior, or a society that can't bear the sight of his nadgers?

By the time a light drizzle sets in, I've got the swing of it. Sure, it feels strange for the first seconds, especially as there's a photographer on hand. It doesn't get easier when two gentlemen from The Sun turn up and start snapping. "Try to be in the present, and enjoy it," says Steve. "If you're in your head, worrying, you won't." He's right. We hit the road, and with every step it becomes less weird, more liberating. Who cares, you think, if nature didn't bless you with the perfect body. Most men don't look like the cover of Men's Health. Bodies are silly and hairy and wobbly.

Confusingly, Steve isn't a naturist. Nor does the British naturist movement support him. "They think I'm a bit in your face; they think I'm a maverick. They want to keep it all confined, to their own strips of beach. Whereas I'm rocking the boat."

Where does this boundary-breaking come from? Steve first got naked in Canada, when he and his partner Alison were living in a sort of commune, and he drove lorries. Until then, life had been quite conventional. He is one of seven children; his dad was a carpenter, his mum a housewife, and they lived in Eastleigh, near Southampton. After school, he joined the Marines because it was what his best friend had done. He didn't like it much, and left aged 21, to go travelling round Thailand, exploring Buddhism, but he never touched drugs. Later he joined the Moonies for a bit. "I was looking for the answer to life. What is it about? I'm very interested in the fact that there's got be more to life than the surface, than getting a job to pay the bills." So he's a questing soul. But dedicating himself to naked rambling wasn't a conscious decision: it was simply that the more the authorities clamped down, the more determined he became.

Has he ever considered giving up? "Of course. But it's reached a point where I can't. I don't like compromising, because then I'm not happy. And my whole thing is that you've got to make yourself happy first before you can make other people happy."

Perhaps the media hype, and legions of fans, feed a craving for attention. Yet he's a self-confessed loner. He doesn't have a girlfriend (though his ex, Melanie Roberts, begs to differ), and says he doesn't miss anyone particularly. "I don't hang out with anyone. I don't need to," he says. Even when I offer my phone, for him to call a family member, he declines. Isn't this is taking the self-centredness a bit far? Couldn't he let them know he's OK?

Steve's philosophy doesn't always add up. He believes that pursuing his own happiness makes him a better person to be around, yet he acknowledges that his own children, Kiana, 16, and Yarin, 14, are mortified by what he does. "I would have been too at their age! I just hope that one day they might get the point of why I'm doing it." In any case, whoever heard of an activist who put their family before the cause?

By the time Milnathort town heaves into view, I call it a day. To the woman who peeled back her curtains to see me getting dressed: I'm sorry. When I catch up with Steve at the petrol station, net curtains are swishing all over the place, and women are getting out their camera phones. Only one, Catherine White, 24, says it's "disgusting". Her three-year-old boy saw it all and got "very upset", so she calls the police. I suggest to Steve he might avoid towns. "I'm not going to start hiding, because then I'd be a walking contradiction."

This weekend, Steve's back behind bars, after being arrested in Fife. Tomorrow, he will appear in Dunfermline Court charged with breaching the peace, and if found guilty, it's back to Perth prison. Is that really the best way we can find to deal with a harmless eccentric? There are murderers who have spent less time inside. At least, for a few hours last week, Steve Gough tasted freedom, and I was glad to be there with him. I even found a new freedom I never knew I'd wanted. Still, it's one I'm happy to live without. I suppose I'm just too used to wearing pants.