He can wield a one-liner with the best of them - 'you only become a man when you stop calling your mum's friends 'auntie' ' - but his greatest skill lies in interacting with the audience. This has put him in huge demand as an MC: the Guardian paid him the ultimate compliment of saying he had 'finally ousted Arthur Smith as our finest compere'. At a show in the Cockpit Theatre, London last week, he showed why, rousing the rabble in a fashion barely seen since Billy Graham's last visit. His technique is to shake the torpid audience into life with insults - 'It's an atmosphere I've only seen before in a library reading- room . . . no wonder fascists take over so easily . . . I should have gone home and rung you up . . . let's all meet up again some time - at a funeral.'
Lamarr dons this likeably provocative stand-up persona to encourage banter, but it can easily spill over into heckling. With this razor-sharp performer, however, he who lives by the heckle tends to die by the heckle. One foolhardy soul at the show was silenced as if by a Bulgarian Secret Service umbrella: 'The whole point of heckling is to make the person on stage look stupid . . .'
Backstage before the show, Lamarr - immaculate in grey suit, round spectacles, Brylcreemed hair, sideburns you could slice bread with - reflects on his often-combustible relationship with his public. 'People do go for me. I've got a fairly aggressive manner. I'm not a philanthropist in any sense of the word. But I like people to join in. I want everyone to be part of it. I don't want it to be me versus 100 people. I want it to be 101 people making a show.'
Over 10 years on the circuit, Lamarr, 27, has never committed a single word of his act to paper. 'All of it has been ad-libbed at one point or another. Everything I've ever done has been written on stage. The comedians I've always loved are the ones that look like they've just thought 'oh yeah'. The only way of doing that - and doing old stuff - is to forget it.'
A lot of Lamarr's schtick revolves around story-telling. 'I pretend these things have happened to me. It's the Billy Connolly thing. You know, every time you see Billy Connolly, he's got a new mad uncle. 'Me Uncle Hamish? - you never mentioned him before . . .' People tend to believe everything. I do a big bit about being a bingo-caller, and loads of people are convinced I used to be one. In fact, I only ever went to bingo once.'
The comedian goes on armed with attitude rather than a script. But this has sometimes proved as much a hindrance as a help. He drew flak for his surprise wake-up techniques on The Big Breakfast (on one notable occasion, he mounted a Gateshead tower- block on a crane, disturbing residents as he went). And on The Word, he attracted criticism for the way he handled interviews with Chris Eubank, Zsa-Zsa Gabor, and Shabba Ranks (a heated exchange about homophobia that caused Lamarr to receive death threats). He also clashed - physically - with fellow presenter Terry Christian. Not for nothing did the tabloids call him 'TV's Mr Nasty'.
'I get accused of arrogance - quite right, I am arrogant, I make no bones about it,' Lamarr says in his defence. 'But who on TV is not arrogant? Maybe the others hide it better than me. By definition, you can't go on in front of possibly twenty million people and not be arrogant. Lenny Bruce said the whole business of showbiz is 'look at me, mum, aren't I clever?' I find it a bit unfair that I've been singled out.'
He's also been singled out as a professional Cockney (no mean feat for someone brought up in Swindon) - another pigeon-hole he resents. 'It's just journalistic shorthand, like 'bequiffed presenter',' the bequiffed presenter says. 'I hate any group that rates itself - especially along the lines of geographical superiority. I don't want to be grouped with anyone else - especially Word presenters.'
Mark Lamarr appears at the Battersea Arts Centre, London SW11 (071-223 2223) on 5 Aug, and at the Assembly Rooms, Edinburgh (031-226 2428), from 12 Aug to 3 Sep