Cyderdelic, Pleasance, Over The Road II

Singers are a mixed bunch. Sometimes they complement and enhance each other, their vocal differences creating contrast and chiaroscuro.

Meet Su, Beetle and Frogger, the West Country trio who make up Cyderdelic. They are less stand-up comedians than crusaders for the environment, anti-government protesters and conscientious objectors to anything that gets in the way of their heavy drug consumption. Frogger never speaks ­ he prefers to lurk in the background twiddling knobs, leaving the sloganeering to his friends.

They are the first to admit that their campaigns aren't always well thought out. Why are they against genetically modified crops? Well, because scientists have modified the genes and that's got to be bad. The biggest laughs come from their collection of television footage that follows their dissident activity. This includes (real) appearances on Sky News (in which they remarked that "the Queen Mother should die soon"), and on Newsnight and Question Time.

The show isn't without its flaws, however ­ they could do with ditching the skit about a fat city worker who befriends a homeless man, for starters. But not since the Alan Parker ­ Urban Warrior show have I seen an exit as inspired as Cyderdelic's. At the end of the performance, they coax us out on to the street where their customised ambulance (the "ambience", of course) appears, complete with a screeching siren, and brings the traffic to a complete standstill.

The word is that they were arrested soon after the crowd dispersed. Now that's dedication.

Venue 33 (0131-226 2428), to 27 August 21.55 (22.55)