You don’t see many satirical revues these days, and the latest show from the comedy-theatre duo the Black Sheep suggests why not. After all, if you put topical comment on stage, you’re entering a buyer’s market. Have I Got News For You. Mock the Week. The Thick of It. The Now Show. The News Quiz. Newspaper columnists. Waggish broadcasters. None of them perfect, many of them glib. But it poses the question: what have Andrew Jones and Ciaran Murtagh, and their director and co-writer Cal McCrystal, got to offer that’s new?

Satirically speaking, not enough. In their past couple of fringe shows — The Joy of Wine and I, Lear — Black Sheep have shown themselves to be an endearingly puerile pair of clowns, smart at being stupid. But their satirical instincts are broad enough not to be out of place in their shows for children, such as Professor Bumm’s Story Machine.

So, although they threaten to throw in routines straight from the news, here they limit themselves to quick quips about Jordan, Miss Great Britain, and — oh no, not again — MPs’ expenses. And when they develop more of a sketch, such as the one about the minister who rejects his scientific adviser’s advice about cannabis, they make their point clumsily; the minister also rejects his adviser’s advice that the world is round. The dad advising his son of the glories of Britain is an unsubtle dig at jingoism. The politician learning the ropes from a hard-nosed old hand is Yes, Minister, but less so.

Performing in sober suits in front of a nifty set, whose House of Commons-like wooden panels open up to allow entrances, exits or even a Nick Griffin impression — Jones, upside down, with beads on his chin for eyes — Black Sheep come alive when silliness subsumes satire.

A look at that day’s paper turns into an amusing origami routine. A dance in bowler hats is under-rehearsed but blessedly without meaning. And when each delivers a solo routine about a childhood moment that helped to develop their politics, The Joy of Politics stops feeling second-hand.

There are some other promising moments in here that just need more editing. But the musical numbers are poor — Murtagh sings Martin Luther King’s “I Have a Dream” to Abba’s I Have a Dream, and keeps on doing so long after the gag’s warranty has expired. Jones’s Winston Churchill dances in baggy gold pants to MC Hammer. They turn the Pet Shop Boys’ Go West to “Go Left”, red banners in hand and Karl Marx wigs on. Even the fresh-faced Murtagh, who can normally motor the duo with his comedic aplomb, looks bashful here.

Black Sheep can be better than this, and surely will be as their run continues and when they take this show on the road next year. But for a pair whose hearts are in daftness, not darkness, topical comedy feels like a wrong turn.

To Nov 22. Box office: 020-8680 4060 www.blacksheepcomedy.co.uk

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