The odd thing about interviewing a comedian, especially over the phone, is that you never quite know when they're being serious. Tommy Tiernan's agent-supplied CV begins with his 1996 Channel 4 comedy award so it seems reasonable to ask him what he did before his sudden explosion on to the comedy scene. "Trainee social worker, apprentice Redemptorist, stage actor . . ." he reels off in his low-key Navan accent. The Redemptorist bit stops me in my tracks given that the last time this comedian was in the headlines was for his less than reverent routine - the word blasphemy was used liberally in reference to it - on the Late Late Show. It caused such a stir that Gay Byrne even apologised for it the following Friday. He has been asked back on the Late Late Show but as he's been on three times already he feels "he's peaked on that and in any case it would be hard to top the last performance".

He was back in the collar again for an episode of Father Ted. "Yeah, I loved it," he says. "The sense of power you feel is amazing." Apart from that he loved the chance to act again. Before his stand-up career he was an actor for four years working with Punchbag and Druid and while his career at the moment is taken up with comedy, he'd love to do more serious acting. "I've a part in Gerry Stembridge's new movie which is being filmed in the summer," he says. "It's called All about Adam and I play a stand-up comedian." The role doesn't fit in with his search for a serious acting part but "you can only take what you're offered", he says philosophically.

Tiernan is one of the busiest and most critically acclaimed Irish comedians working on the circuit. Last year he co-headlined the Edinburgh Festival with Jason Byrne and this year he'll be going back there with his solo debut. It's a life and times of Tommy Tiernan-type monologue, snippets of which will be familiar to fans who saw his recent Irish tour. He says his rambling monologue style is inspired by the ironic super-laid back Spalding Grey and by Eoin O Neill.

Despite winning such critical acclaim there he has mixed feelings about the Scottish festival. "The thing that's great about the Cat Laughs, is that by comparison with other festivals it's so relaxed," he says. "Edinburgh is like 21 bad birthdays come together." His days are currently taken up with rehearsing a pilot for a sit com for Channel 4 and he's also writing material for a half-hour TV showcase that will be filmed in the Town Hall theatre, in Galway, for Channel 4. Tiernan has been described as a prolific writer and he's testing that by writing a novel. "I know it's nearly the thing for Irish comics to do," he says, adding that he has just finished reading Ardal O'Hanlon's book which he really enjoyed, "but it's the chance to write something and not be a slave to the joke". What he will do with the book if it is ever finished is difficult to say. He has already written several short stories but has, by his own admission, never had the confidence to show them to anyone. It's a curious admission for someone whose work is on show for immediate judgment every time he does stand up. He lives part of the time in London because that is where the work is but his other home is in Galway - hence the choice of location for the Channel 4 showcase. He was born in Donegal and brought up in Navan but since his days with Druid discovered that Galway is "an excellent relief from hot, smelly London".

Tommy Tiernan performs in the Village Inn, Fri 11 p.m., Kyteler's, Sat 8.15 p.m., Sun 8.15 p.m., Mon 10.15 p.m.