I Bought a Blue Car Today, Vaudeville, London

There seems to have been a recurring clause in Alan Cumming's contracts that has obliged him to bare his backside at most of his theatrical ventures. From his sleazy Emcee in Cabaret to his drag Dionysus in The Bacchae, we've come to know those buttocks like the back of our own hands. Fans hoping for a flash of rump in his one-man musical show of songs and reminiscence at the Vaudeville are in for a disappointment.

The impish Scot is not only fully clad throughout but dressed down in anonymous casuals. His little bleached-blonde wedge gives him a look of Tintin. And barely any use is made of the promising black chaise longue that is the sole item of furniture on the stage he shares with his excellent band. Oh, he's naughty, all right, but here in the guise of the returning prodigal ready to regale us with name-dropping (occasionally hilarious) anecdotes about his 10 years of adventures living in the US.

Indeed, the odd title of the show comes from his application for American citizenship. "I bought a blue car today" was the sample sentence he had to write out as part of his naturalisation test. At first he thought this was sweet and child-like; then it struck him as epitomising the gas-guzzling consumerism of the culture. No, the level of political comment is not high. There's a salute to Britain and its gay rights record (he and his boyfriend came over here to marry). There's the odd genial gibe at the US – "naturalisation", he remarks, implies that it's unnatural to be non-American. But, in general, he revels in his dual nationality – the US is lauded as the land where Alan found celebrity before he'd even got the hang of just how iconic were the honours being offered him (singing at Carnegie Hall, hosting Saturday Night Live etc).

He tells one hysterical story of failing to recognise Walter Cronkite when on the prowl for a dance partner in the audience of Cabaret and it's all the funnier because the eminent veteran gets the last laugh. But there's a surfeit of chummy, faux self-deprecation and the maudlin is in danger of outweighing the mordant in the musical numbers.

Cumming has undeniable and indefeasible charm. But what has happened to the scabrous Scot and the louche, sacrilegious elf? They seem unduly restrained in a piece that began life in New York and has perhaps miscalculated the degree of ingratiation needed on this side of the Atlantic.