Ricky Gervais, Soho Theatre, London

How reputations can change. A couple of years ago Ricky Gervais was known, if at all, for his appearances on various badly received Channel Four shows as a bumbling, calculatedly tasteless interviewer, and, to London radio listeners, for a freeform show on XFM alongside the equally obscure Steve Merchant.

Now, because of the extraordinary success of the pair's The Office, rightly acclaimed as the best sitcom since I'm Alan Partridge, the wildly exaggerated traits which once put people off – a certain propensity to superciliousness, a marvellously insincere smile – have led to him being hailed as the best thing to happen to British comedy in years.

Yet despite a long career on the fringes of performance, Gervais has never previously managed an hour-long set as a stand-up, so this show is a step forward.

After the introduction, which consists of a short nature film with a talk-over from Gervais in a corny French accent, amusingly confusing animal and human sexuality, the man himself gives us an hour-long "lecture'', with many digressions.

Claiming to be cheaper than David Attenborough and putting himself forward as a potential replacement, Gervais, a confirmed addict of documentary channels and thus "an expert on sharks and Nazis'', rambles wildly. He explains that the most destructive animal on Earth is the giant gorilla by showing a slide from King Kong, how God, like David Blaine, simply doesn't need to explain how he does it, and describes Stephen Hawking as pretentious. His evidence? "He was born in Kent and now he speaks with an American accent.''

Most impressive, though, is just how good he is at sustaining an hour-long show. As parts of this set were debuted at last year's Edinburgh Festival in a short slot, he's relaxed throughout and copes easily with interruptions.

The Big Brother references wilt as they leave his mouth, but this blend of genuine erudition and magnificent ignorance is sometimes jaw-dropping, especially the illustrations of gay dolphins. It's safe to say that no performer working today does a better impression of a lesbian marmot.