NOW in its second year, the London Comedy Festival has a way to go yet before it is firmly established. Avalon, the largest comedy management stable, has still to be persuaded to let its acts take part, and there are many venues in the capital better suited to laughter than the Riverside Studios. The white-walled foyer amplifies interval chatter to painfully high volume levels, and, as Mark Lamarr points out, the banked seats of the main auditorium prompt uneasy memories of Pink Floyd at Earls Court. Happily, such discomfort is his stock in trade.

Lamarr's triumphantly dignified showing in the face of the cruel "Fifties Throwback" jibes of Shooting Stars' hosts Reeves & Mortimer won him many new admirers. In his various earlier TV-presenting incarnations, his keenness not to be seen to have been co-opted often made him appear brash and arrogant. On stage though, dressed as he is for the bowling alley, there is an openness, even a vulnerability, about him that is extremely likeable.

As a compere, Lamarr still strikes a somewhat unsettling balance between amiability and aggression: picking up individual audience members on the quality of their laughter and deliberately depressing everybody before rival acts come on by talking about the death of Bob Marley. At the interval, he decides to punish the crowd for the alleged parsimony of their response by remaining on stage until they feel obliged to slope off one by one, authentically embarrassed. "You've not made it easy for me," insists the Swindon spiv, "so I'm not going to make it easy for you."

When the time comes for Lamarr actually to do his act, there is some danger that his relentless causticity will have put everybody in a bad mood. At this point he cannily turns his heightened critical faculties on himself, chasing his own syntactical tail until his whole speech pattern starts to break down. "I waste a lot of time saying the same thing over and over again," he confesses gamely, "and I've said that before haven't I?"

Lamarr's remorseless self-deprecation is not embarrassing - as, say, Lee Evans's can be - but actually conveys something quite interesting about the nature of comedy. "It's like I've been pissing on fireworks all night," he observes ruefully as the show draws to a close, "and now you're all looking at me saying, 'Come on Mark, where's the display?' "

As a writer of prose and poetry, Sean Hughes has a seemingly unattainable ambition: to make Robert Newman look like a significant literary figure. As a comedian, however, he has still got what it takes - though you wouldn't know this from the first hour of the show he obligingly does for free at the Riverside. Other nights are being filmed for Christmas broadcast on Channel 4, and a certain amount of hard labour is going to have to go on in the editing suite if the target audience are not going to be reaching for old Crimewatch videos halfway in.

Where Lee & Herring, 1995's sixth-form comedians of choice, are happy to wallow in the youth and impressionability of their target audience, Hughes has long seemed uncomfortable with the tender years of his prime constituency. His attitude at times seems almost disdainful, as he veers uneasily between talking down to his audience (heaven preserve us from bad Damon Albarn impressions - the real thing is tricky enough to cope with) and going wilfully over their heads. One Winston Churchill and Nancy Astor reference is so reluctant to give itself up that a detective chief inspector has to be called in to talk it down off the roof.

What makes Hughes's compulsive underachievement so frustrating is that at his fun- niest - dissecting dysfunctional family relationships or Dublin lounge decor, for example - he is a truly challenging performer. He has a real talent for undermining the assumption of shared experience on which so much second-rate comedy is based. "Did you ever do that thing," he asks, in the casual vernacular of a thousand arrested-adolescence gags, "of feigning serious injury when your dad hit you?"

'Sean Hughes is Thirty Somehow': 10.10pm, C4, 22 Dec.