Comedian Tommy Tiernan takes to the road in a new series that takes story-telling a step further. Arminta Wallace walks a mile in his shoes

'We set out not knowing what was around the corner - literally," says David Power of Power Pictures, producer of the four-part television series Supertramp, which starts tonight on Network 2. The idea was simple enough: take one touring stand-up comedian - Tommy Tiernan - have him walk from venue to venue and follow him with a camera crew.

"We wanted to get out there and examine the art of story-telling, which is what interests Tommy as a comedian. We also wanted to see what's on our doorstep - and look at it from a slower pace than if you were in a car, or going by on a bus, or whatever." But hang on a second. Walk, did you say? Walk? Around Ireland? Is this some kind of punishment/ penitential thing?

"Mmm," Tiernan muses. "You mean like Robert de Niro in The Mission, carrying my rucksack up the mountain and then disappearing over the waterfall? No. But I definitely wanted to do something strenuous. There's a feeling that you get after doing something physically strenuous - the chemicals that are released are good for your head. I also wanted to get a bit of air. When you travel these days, a lot of the time you're hermetically sealed; stuck in a car or an airplane or a train, totally removed from the environment that you're travelling through. And my lifestyle is pretty urban. I mean, I knew at the back of my mind that rural Ireland was out there somewhere, but . . ."

From idea to reality is, of course, itself an interesting journey. As Tiernan and Power rapidly discovered, rural Ireland ain't what it used to be. "I had these romantic, Patrick-Kavanagh, hobo-type notions of tramping the roads and engaging in earthy conversations with farmers leaning over the half-door," Tiernan recalls, with a chuckle. "But you don't meet anything much on the roads of Ireland except trucks.

"The low point came somewhere between Newbridge and Portlaoise, when I had to be rescued from the grass verge. I thought I'd have big open spaces for thought and creativity, but in fact, listening to cars and trucks whoosh past you all the time is like being followed around by a wasp. I knew the walking itself would take a lot of effort, but I didn't realise how much I'd have to concentrate on just making sure I didn't get killed."

The team also fell foul of that familiar drawback of summertime Ireland: the weather. "Initially, I think Tommy had envisaged drinking porter by the side of the road and having the sun set on his shoulders as he crossed the mountains," says Power. "But it turned out to be the wettest May since 1758."

After a couple of days of trudging through sheets of horizontal rain, Tiernan admits that his romantic notions about the health benefits of long-distance walking were somewhat shaken and stirred.

"I got blisters the very first day. I bought these special non-blister socks - but they must have been seconds. And I was starting to feel aches and pains in different parts of my body. But my favourite part of the day was going into the chemist and buying bandages. After a while I really felt like somebody who was qualified to do something, going into a chemist and saying, 'Hi! Do you have any tendon straps, or maybe thigh braces?' "

For the production company Power Pictures, the demands of the tour dictated the pace and shape of the programmes. "Of the 42 days that Tommy was on the road, we shot about 20," Power explains. "In terms of film-making, the point was that he had an itinerary with dates and venues that he had to reach, so he had to achieve a certain amount of mileage each day. It wasn't a situation where we could say, 'Oi - could you just walk back there and do it again so that we can get it from another angle?' It was a case of shooting it on the hoof and try to capture the whole thing as it was unfolding. But that was what we set out to do, anyhow - something that was spontaneous and free-flowing."

It is to the credit - not only of Tiernan and Power, but also of director Pat Comer and editor James Dalton - that the finished programmes present a quietly quirky view of an Ireland which doesn't often make it on to prime-time telly. From the desert moonscape of the Burren to the rolling drumlins of Cavan and Monaghan, the landscape is beautifully photographed, and the observation of people is unexpectedly gentle. As an elderly bachelor quotes the blood-soaked lines of a Catholic battle hymn in a soft Midlands accent, the camera finds his gnarled, shaking hands. "This world will crumble and decay . . ."

An eclectic soundtrack adds to the fun, commenting on the action in accents ranging from country through blues and flamenco to jazz. In the course of his journey, Tiernan meets the storyteller Eddie Lenihan, the writer/ philosopher John Moriarty, a gang of laid-back bikers and a team of African soccer players. When he goes to tea with an enclosed order of nuns, he's asked; "would you like some tart?" "I was going to make a joke there," he replies. "But I think I won't."

Nevertheless, he is in the business of creating comedy, and Supertramp is unflinching in its portrayal of Tiernan as a working comedian. Snatches of conversation are transmuted into strands of stand-up. "Money won't make you happy, it'll make you fuckin' fat ." "If people want to spend a month in a refrigerated truck in order to come and live in Lahinch, well, I think they should be let . . ."

The camera records it all: bursts of laughter, stony faces in the audience; Tiernan prowling the stage like a tiger; Tiernan slumped in a corridor, unshaven; Tiernan arguing the merits of knob gags with a parish priest. What is his bottom line, then, as far as material is concerned?

"You can become too . . . what's the word? Not constipated. Constricted. You really just have to move freely through subjects, and if, sometimes, you're talking about sex, well at least do it joyfully and don't be apologising for it. If there's something I find funny about sex, I include it. If my whole show was about sex I'd have to say, 'Well, Tommy, look - there's more funny things in the world than that'. I have a bit about sex in my new show which is absolute pure filth, and I love doing it, but out of an hour and a half show it's only about a four- or five-minute story."

AS Supertramp begins its run on Monday nights, both Tiernan and Power have moved on to other projects: Power to documentaries on Irish wedding planners and the Venezuelan president Hugo Chavez, Tiernan to recording Roddy Doyle's The Giggler Treatment for BBC audio. "And can I plug my new video? It's called Tommy Tiernan Live, and it's out on November 1st." But seriously. "Supertramp is going out against The Office on Monday nights, so I think we're going to be hit very heavily in terms of comedy viewers. Still. Maybe some old people will watch it.

And I hope they enjoy it . . ."

Supertramp - Tommy Tiernan's Walking Tour of Ireland is on Network 2 tonight at 9.55 p.m.