Star Struck / The Wicker Woman, Jermyn Street Theatre, London

One limp Ethel Merman imitation might be accounted a workaday misfortune for a critic. Two within a week, and it starts to look as if someone has it in for me. After Call Me Merman at the King's Head Theatre (reviewed yesterday) comes David Benson's Star Struck. His ineffectual braying, however, was the briefest and least offensive impersonation in the show, half of a double bill more tawdry and feeble than any I can recall, unless I have reached the lower slopes of Mt Alzheimer sooner than I thought.

Benson begins by asking the audience which famous person, living or dead, they would invite to dinner, and why. The answers are not what you would call sparkling - one man said he'd ask Noël Coward, because "I loved his plays". If involving the audience is intended to make Benson's patter shine more brightly by contrast, it fails. Benson would also invite Coward he says, because "there was something about him". As a lonely suburban boy, Benson tells us, he worshipped the great entertainers and got close to a few. Groucho Marx, at his request, sent a signed photo. Eric Morecambe gave the boy his autograph. Frank Sinatra - well, they never met or even wrote to each other, but when he came to the Albert Hall, "I was there! I was breathing the same air as Frank Sinatra!"

At this point in such exciting reminiscences, somebody usually changes the subject so that no one, driven mad by boredom, murders garrulous Uncle Dave. But Benson, unimpeded, goes on to imagine that he attends the all-star party of his dreams, with Coward as the host.

As well as imitating his heroes, with varying degrees of success (Coward is pretty good, Quentin Crisp sounds rather like Winston Churchill), Benson puts a lot of foul-tasting gags into their mouths. Sinatra is depicted as urging Marilyn Monroe and James Dean to kill themselves in order to preserve their legends, addressing a disgusting remark to Ava Gardner, and caring only about making money and holding on to it. (Whatever else one could say about him, Sinatra was in fact a generous contributor to charity.) Coward makes repeated advances to Benson, who is gay but doesn't fancy him. The performance seems an exercise in revenging oneself on the famous for being unaware of their fan's existence - but the spectacle of obsequiousness curdling into resentment is neither clever enough to be funny nor passionate enough to be disturbing.

In The Wicker Woman, a young man and two pretty girls throw their energies into a parody of the 30-year-old thriller about the sacrifice of a virgin by a pagan island cult. There is a lot of running about and shrieking, an imitation of Freddie Mercury, and a display of a turd said to resemble Jesus on the Cross, all of which is about as amusing as the subject is topical. In this type of show, the inadequacy of the set and props is often used to comic effect, but here they simply look cheap and ugly.

Both shows are directed by David Sant, a founder of the comedy troupe Peepolykus. They suggest that the self- advertisement of the title has hypnotised him into a false sense of invulnerability.

To 17 January (020-7287 2875), then touring