Tommy Tiernan is one of those comics whose profile just doesn't match up to his talent.

He may have won the Perrier in 1998, but it was his runner-up, Peter Kay, who got the comedy cream. While the Phoenix Nights star can fill vast theatres many times over, Tiernan remains something of an undiscovered gem in Britain, no matter what exposure he may have received from his stint hosting BBC1's Stand-Up Show and his Channel 4 sitcom Small Potatoes.

No doubt the aim of this current tour, which culminates in a run at the Edinburgh Fringe in August, is to bring his image in Britain closer to the status he enjoys in his native Ireland, where he is something of a stand-up superstar. Just a week before this low-key gig in front of a small, reserved but appreciative Home Counties audience, Tiernan was storming sweaty, packed-out rooms in Kilkenny's Cat Laughs Comedy Festival, performing to 'his' people.

In fact, he seems equally at home with both audiences, able to employ the cheeky quick-witted banter demanded by the baying mobs, yet backed with sharp, intelligent material to satisfy those wanting something meatier in their comedy.

Take his routine about his schooldays. It's material that doesn't entirely shy away from the usual 'Anyone remember Spangles?' brand of easy nostalgia, but he uses that to provides a backbone of guaranteed laughs around which to explore more incisive themes about the loss of childish imagination and the onset of conformity.

Tiernan is also expert at making a strength of his failings. He admits to being a depressive, comparing his life to that of a morose whale skulking in the lower reaches of the ocean, only to surface for one moment of glory ­ a gig - before returning to the murky depths from where he came. Only he makes this analogy funny.

His is a lyrical, almost literary form of stand-up, full of sparkling allusions and incisive metaphors, with even the most mundane of observations decorated with poetic flourish.

He also plays up his shambolic manner, employing the sort of delivery that makes his material feel loose, spontaneous, ill-thought-out, even. Yet it's a subtle illusion, as miraculously he manages to hit every sharply-written line bang on the nose.

The scatterbrained style has other advantages. Like a jazz musician, the words that he doesn't say are as important as the ones he does. The analogies that deliberately dissipate into nothingness and the obvious silences after a monologue fails to climax in anything even vaguely resembling a punchline provide natural breaks in his patter into which laugher instinctively falls.

But lest you think this show is all too clever-clever, its cornerstone routine is little more than Tiernan repeatedly saying 'up the bum' in the sort of cod French accent that would be thrown out of Allo Allo for being just too affected. Still, it is very funny - and the tale has a fantastically memorable ending.

The only shame is that all this wonderful material doesn't gel into a coherent show. The big ideas brought up are too often left hanging, in need of some inspired ending or theme to tie all the threads together.

Instead, Tiernan distracts himself by embarking on conversations with the audience. He's competent enough at this two-way banter, but it seems pretty flyaway compared to the weighty issues tackled so deftly earlier in the show.

While this tour is unlikely to give Tiernan anything like Peter Kay's pulling power, it will reaffirm his considerable talents, further endear him to his existing, loyal fans, and, hopefully, attract some new ones along the way