Stephen Gough, better known as the Naked Rambler, rubbed musingly at the great grey beard which spilled like a waterfall from the crag of his chin. "You can stay in my tent," he offered. "As long as you don't get naked."

My night with the Naked Rambler. It has the air of a scandalous confession, and yet was more enlightening than erotic. I am, I believe, the only journalist to have slept with him in his tent. I learned a lot from our time under canvas and walking together through the Scottish countryside. I came to believe that he is a more rational, more focused individual than the media portrayal of him has lead us to believe, and to feel certain that the public are more tolerant than the legal system which is supposed to protect us from the sight of his nude body.

Gough, now in his early 50s, has since 2006 spent much of his time in prison, as a result of his insistence on going unclothed in public, including in jail and during court appearances. When I met him, in October last year, he had just been released from Edinburgh's Saughton prison and planned to walk nude to his home town of Eastleigh, near Southampton, to see his family for the first time in years.

A film crew recorded each determined footstep, following him through the biting winter; over 400 miles and four months, he was arrested eight times, once while attempting to buy flapjacks. The tragicomic documentary is on BBC1 next week, and I make a brief appearance, taking notes as Gough poses for pictures with amused road workers, or else struggling to keep up as the former Royal Marine powers ahead with a great yomping lope.

Public reaction to Gough, in the flesh, is overwhelmingly positive. He is stopped all the time for handshakes and photographs. Few understand that he regards himself as a martyr for personal freedom, or that he sees public nakedness as a vocation. Rather, he benefits from a British taste for eccentricity and sauciness. Walking near Penicuik, Gough passed a village hall where a bake sale was being held, and nodded to the middle-aged ladies who came out to greet him. "I'm just damned disappointed," said one, "that I didn't have my glasses on." It was the same the whole time I spent with him – smiles, waves, honking car horns.

Much has been made of his refusal, while in custody, to take part in mental health tests. Having talked to him for hours, I believe Gough to be sane. He has had plenty of time to rehearse his thinking, so has an answer for everything, even the difficult question of why he has hurt himself and arguably his children by spending years in jail while they grew up. Not seeing them was hard, he said, but he feels he has set them an example of how to live a life of integrity.

In the tent, we lay together, his feet by my head. He is uninhibited in many ways, belching and farting with apparent gusto. Maybe it was the whisky, maybe it was the years in solitary confinement, but he was still in the mood to chat. "If you compromise your truth," he insisted, "you compromise yourself." And then he started snoring.

When the documentary airs next week, Gough will be back in custody, having been arrested today for being in breach of an asbo that insisted he cover up. So, as the nation tunes into the Naked Rambler's adventures on the road, he will once again inhabit the curious paradox that has marked his last few years – standing up for freedom while lacking any of his own.