The combination of politics and comedy in the stand-up of Rob Newman has often seemed uneasy. But never more so than in his new show, No Planet B, which - at least on its press night - is less funny and politically potent that its recent predecessors. Newman has struck on an idea with terrific comic potential: "I shall," he announces, "be telling the history of the world - backwards." This is a world in which society becomes less technological as time passes, in which Charles Darwin finds that humans are evolving into chimpanzees, and in which the suffragettes campaign for fewer rights for women - and succeed.
But Newman isn't wringing the best from his premise. And he sometimes seems apologetic for using comedy as the means of trying to do so. It can be difficult to navigate the holes in his internal logic - not least because the milestones at which Newman pauses (the Black Panther movement, the US/UK-sponsored overthrow of Iranian democracy) are not especially familiar ones. Meanwhile, there's a tangential subplot about a Spanish civil-war love affair, which feels more like the creation of Newman the novelist than Newman the stand-up. His comic songs (played alongside backing musicians Diego Brown and the Good Fairy) are less effective than usual and, in one instance, unintelligible.
It's frustrating, because No Planet B has the makings of a very entertaining and pungent show. Newman's not-at-all-comic thesis is that a return to primitivism is what's in store for us if we continue to destroy the world. His show ends with an extraordinary monologue in which humankind narrates its descent back to the primordial swamp. And yet there are choice laughs along the way. "Milton," we're told, "started using the words 'thou' and 'thee' because he'd been listening to the Kaiser Chiefs." Should Newman himself go backwards, at least as far as the drawing board, this show may yet make progress in the right direction.
· Until July 15. Box office: 020-7328 1000.