There is something mildly disturbing about the way many Hollywood stars used the tragedy of September 11 to give their careers a boost.

The fires had barely begun to die down at Ground Zero when Michael Jackson announced he would be releasing a charity single and it can only be a matter of time before we are subjected to 9/11 - The Musical.

I have no doubt the Jackson song would have been a sentimental ballad about healing and stayed at Number One in America's charts for about a billion weeks.

So we should perhaps be thankful his attention was diverted by more pressing personal matters and it was never released.

It might not seem an obvious subject for comedy but it is this over-sentimental and at times cynical response to the toppling of the Twin Towers which preoccupies drag act Chris Green.

His alter ego Tina C, a self-obssessed Country and Western doyenne, offers a shrewd critique of America's role in the Middle East and the sentimentality which tends to short circuit rational debate about September 11 on that side of the Atlantic.

The trouble is, she just isn't that funny.

The premise is that Tina C is a jobbing Nashville singer who has used 9/11 to boost her flagging career with a series of crass songs about healing and the naff patter of the worst touchy-feely self-help guru. The joke works in much the same way as Private Eye's Warballs column, which lampoons lazy journalists who constantly make the most spurious references to "post 9/11" and its effect on the most banal news events.

But the difficulty with apeing a mediocre act is always that your routine runs the risk of becoming the very thing it is sending up.

The best way to avoid this is to have a lot of genuinely good jokes - and this is where Green fails.

The audience warmed immediately to Tina C when she stepped out at the Spiegeltent in a tiny rhinestone-studded dress and a cowgirl hat.

They clapped along during the songs and waved their arms when asked to but the act was short on belly laughs.

Green's material relies more on the telling than the jokes themselves.

"I made Arial Sharon hoot with laughter at the joke I made about his name, as did Yassar Arrafat - though I did run into trouble with the Indian Prime Minister, Mr Vajpayee," Tina C deadpanned.

The joke is as lame told live on stage as it appears in print but a generous audience guffawed at Green's insouciant delivery.

Tina C spends a large part of the show touting her CD ("I think it's important that you purchase") and croons most of the tunes.

The lyrics are full of clever political barbs but - like the rest of the show - are rarely funny and rely on Green's kooky delivery.

So he tries too hard and the songs begin to grate, particularly the operatic disco version of Puccini's Nessun Dorma.

This slick production deserved top marks for effort. But it was long on satire and saucy songs and short on laughter.