Party, Arts Theatre, London

What coronaries, kittens and caterwauling tantrums one would have – doubtless simultaneously – if one could eavesdrop on a political party's HQ when it was awash with bad faith at manifesto-writing time. So it says a lot for Tom Basden's play-making skills that he has managed to concoct a charmingly funny comedy about the process. We're not talking David Hare here. Basden's satire is gentle and oblique and it derives its beguiling mix of acuity and tactical daffiness from the fact that, far from being professional politicians in Millbank, the five twentysomethings whom we follow through 70 minutes of inconclusive bickering are incompetents hard put to come up with a name for their organisation, let alone any mutually agreed policies beyond "democracy" and "space programme".

The latter they realise probably has no legs financially, what with the need for cuts. As for the former, well, there's so much deliciously petty tetchiness within the group that general principle falls foul of particular peeves at every turn. Did I mention that they are holed in a garden shed that belongs to the offstage, Buddhist-chanting mother of Jared (Jonny Sweet), a young man in whom the oppressively reassuring manner of a latter-day vicar does battle with serene intellectual dimness and delusional desire to be Prime Minister? They know how to go through the motions of canvassing one another's ideas and taking votes, but you would not trust this lot to run a single bring-and-buy stall for some disaster relief fund.

Insofar as we have a representative onstage, it's the hilariously hesitant, apparently slower, yet intermittently sharper Duncan, beautifully played by Tim Key. He's there on a misunderstanding. It's his birthday and he mistakenly, well, you can fill in the rest. There's a lovely routine where Duncan, a suited "square", pours water for everyone and, in a manner that may or may not be conscious subversion, fills each glass to the absolute brim. The play, too, is a perfect fit for its projected dimensions and boasts terrific performances from the author as the bolshie Jonesy, Katy Wix and Anna Crilly as two females who are prepared to play fast and loose with political correctness, and Nick Mohammed as an interloping would-be boyfriend whose callous dismissal rather exposes the Party's claims to humane inclusiveness.

To 13 March (0845 017 5584)