An irresistable piece of theatre lights up the West End in time for Christmas. Absurd Person Singular offers a perfect antidote to the cloying bonhomie of the season and an evening in which waves of laughter give way to clouds of pathos.

Premiered in 1972, Alan Ayckbourn's comedy of social embarrassment and marital unhappiness shades into cruel black farce and even absurdity in the second act.

It ends up cleverly inciting us to smile through gritted teeth at the spectacle of two middle-class couples, who vainly try to keep up appearances that insist upon falling down.

Staged in three acts, three unlovely kitchens, on three successive Christmas Eves, with three actresses in high comic/pathetic form, Absurd Person Singular has not dated an inch, or rather a centimetre, since it premiered.

Only the clothes and kitchen accessories show their age. Ayckbourn often proves himself at his sharpest and funniest when revelling in the games British people play over questions of class and duly demonstrates how the insensitivity and egotism and ignorance of two hopeless husbands drive their wives to drink and worse.

The playwright directs his scorn at people too self-absorbed to notice someone in their midst is trying to kill themselves.

The comedy is launched in the hideously decorated, lower-middle class kitchen of Jane and Sidney Hopcraft, an upwardly-mobile couple in trade who are all of aquiver over the arrival of their socially superior friends.

The Sidney of David Bamber, an actor whose gesticulating hands regularly put on the most excessive, almost non-stop show in town, do their familiar waving.

Jane Horrocks, delectable and amusing as Jane in her Marigolds and high degree anxiety, flutters around indulging an escapist obsession with cleaning.

As wife to David Horovitch's fine, true-to-life, eternally unaware bank manager, Jenny Seagrove's Marian puts on a brilliant comic show and ultimately a poignant one.

Condescending from a great height, she admires work-surfaces and drawers as if they were works of art, yet soon slips into the blur of alcoholism.

Lia Williams's Eva, wife to John Gordon Sinclair's bland architect, Geoffrey, tumbles even further when, apprised of his adultery, she passes act two in eloquent, grief-struck silence.

Williams's wordless, terrific performance speaks sad and farcical volumes as she attempts varieties of suicide in her own kitchen - her head in the oven mistaken by Jane as a cleaning mission she will gladly take over. Ayckbourn slips into funny, bad taste absurdity here.

His last act coda, though, all bittersour humour - the middle-class couples brought low - pertinently marks the ascendancy of the ghastly, nouveau riche Hopcrofts. It was seriously pleasurable.