TOMMY Tiernan received an unexpected 34th birthday present this week: news that his June 28 show had been selected as the Headline Event of the first York Comedy Festival.

"Headlining it? I didn't know that, but I'm sure I deserve it!" he says, on the hoof on his mobile phone in Dublin, walking to St Stephen's Green to toss bread to the ducks on the lake.

The Irishman likes surprises, seeking to surprise himself and his audience with his gift for whimsical improvisation.

"My ambition is to walk out on stage every night and create something special, and the bottom line is that it has to be funny. My intention is to shake the walls wherever I play every night," he says.

How does he judge a good show?

"If people leave bits of clothing behind, or if they just leave anything behind... as a deliberately romantic gesture or if they have a feeling for the room," he says.

Making each show different from the last is essential, Tommy believes. "Otherwise it's a recital and my kind of comedy is not a recital. It's like cooking for guests; there's a pressure there.

"The most important thing is to go out there and make sure that the evening is not hollow for me or for the audience. It comes down to commitment: the performer must be committed to the audience," he says. "Each night, I'm going to rip through it and give you a performance."

Bound for the Edinburgh Fringe in August, his latest show is a celebration of story telling entitled Tell Me A Story... From Inside Your Head. "The title came from one of my children, Jacob, who's four. One day he said 'Tell me a story' and I went to pick up a book, and he said 'No, no, tell me a story from inside your head'," Tommy recalls.

"I started to work on it about a year ago, and I've been getting up on stage for that year trying to get to the bottom of the show. It's changed 100 per cent since I started."

Explaining the format of Tell Me A Story... From Inside Your Head, Tommy says: "The stories are composed on the tongue, 85 per cent from existing material, 15 per cent improvised. Part of the evening involves stories, part of it is about the philosophy of stories."

Brought up in Navan in Southern Ireland, he is steeped in storytelling with a humorous punch.

"The town where I grew up was strong on wit, especially strong on sarcasm and barbed wit, but not entirely cruel. There was lots of verbal jousting," he says.

He now lives in Galway on the West Coast. "It's a beautiful place to be; we're just 16-17 seconds from the Atlantic Ocean... you kind of gel with it.

"I was 18 when I left home - it was either leave home or marry my mother, and I decided she wasn't tall enough."

He attributes his love of performing to his childhood days. "It comes from being unloved as a child," he says. "The number one reason is the feeling that you have something to say, and number two is the desire to please others."

He has certainly done that, winning the Edinburgh Fringe Perrier Award and Best Stand Up honour at the British Comedy Awards in 1998; playing sell-out runs in New York, Australia and New Zealand; performing to 25,000 people in Dublin on his latest tour; and starring as the manic depressive Father Kevin in the cult comedy Father Ted.

"It is gratifying to win and it's great to have your hopes confirmed to keep you going, through an award or a review, but ultimately winning an award doesn't really make a difference - other than giving some reassurance to the performer and audience that he's not rubbish but good at what he does. It says 'OK, you can trust him, he's good'," says Tommy.

There was, however, a down side to those 1998 gongs. "I was blinded by the lights. I did loads of television when I wasn't sure why I was doing those shows. I was doing them just because I was offered them," he says.

"I'd been very ambitious to win the Perrier but once I won I didn't have a next ambition. Now I'm back where I want to be, just making every night live and exciting for me and the audience, keeping it funny and joyous without being too frivolous. I want to keep hold of the good vibrations."

Tommy will be appearing soon as a panellist on Call My Bluff on daytime BBC1 - "It's life in the fast lane," he jokes - and his tour rolls on towards Edinburgh. "I never give away what will be in the show. I'll be talking about stuff, S-T-U-F-F, loads of stuff," says Tommy, whose past subject matter has embraced Irish tinkers, fatherhood, the death of close friends and 400-year-old potato women. "I always like to keep an audience surprised."

Now comes the pressure of headlining the first York Comedy Festival. "I can feel it," he says. "I'm verdant!"

Tommy Tiernan, York Comedy Festival Headline Event, York Barbican Centre, June 28, 8pm. Tickets: £15 on 01904 656688.

Updated: 11:31 Friday, June 20, 2003