Only a handful of comics, bred in the spit and sawdust world of comedy clubs, are capable of making the leap successfully from 15-minute spots in such venues to a full hour on the Edinburgh Fringe, let alone a full length show; and from a one-nighter in the West End to a full run.

All those jumps, however, have been successfully, and seemingly effortlessly, made by Ross Noble, who, for two or more blissful hours that seldom pall, conjures up an entire parallel comic universe. Not since Eddie Izzard has a stand-up arrived on the scene of such inspired freewheeling comic imagination than Noble, who likewise seems to be making it all up on the spot as he goes along.

No two Unrealtime performances will ever be alike, since so much is built around his interactions with the audience. Yes, there are some set pieces that you know are being 'fitted in', but Noble has the seamless and peerless ability to make the show feel both organic yet constantly surprising, even to him.

After making casual (and, I hasten to add, non-threatening) connections with a few members of the audience, Noble collects up strands of stories he builds up around them and binds it together in the most dazzlingly accomplished 'spontaneous' comedy I've ever seen.

"It's not the most linear of shows", he admits - "just think of it like an episode of 24". Somehow he encompasses Hare Krishna's on Oxford Street and a tramp who gets embroiled up in their midst with a spot-on impersonation of Stephen Hawking.

But it's the quick-wittedness of his dialogue with the audience that constantly astounds. Finding a member of the audience is from Brazil, for instance, he tells us that it's famous for nuts and waxing - and as a result, produces "some of the best postcards you'll ever see."

Noble has an amazing loose-limbed physicality, too, and sheer likeability that makes an evening spent in his company pass in a wave of laughter.

- Mark Shenton