You Write The Reviews: The Seventeenth Valentine, White Bear Theatre, London

At a small fringe theatre in south London, I saw a gem of a play this week from a writer who surely has a great future ahead of him. Russell Mardell's The Seventeenth Valentine is set in Alan Ayckbourn territory. Two married couples who are poles apart are thrown together in unusual circumstances, and old wounds slowly ripple to the surface. Yes, this may sound familiar, but in Mardell's writing, themes are interwoven and mood carefully orchestrated as each spark flies and another layer is carefully peeled away.

It is billed as a "bittersweet comedy", and it is very funny – I haven't laughed out so loud in a theatre for a long time. But it also touches raw nerves, and it's impossible to watch without a sentence or an action reminding you of someone you know – perhaps even yourself.

A middle-aged man, set in his ways, is trying to write the book that is supposed to be in everyone. His younger wife wants another, better life, and communication is virtually nonexistent except when they argue. Into this fiery cauldron walk a husband and wife who, through genealogy, have discovered that they are related to the other couple. Shockwaves start to flow and skeletons fall out of several cupboards.

The small ensemble is brilliantly cast. Nicholas Lumley, in the pivotal role of the aspiring writer, turns in a virtuoso Basil Fawlty-like performance as he rants and raves at everyone, yet crumples into pathos when sad truths begin to seep out. He holds the attention magnificently, and even when he is not speaking, his face tells many a story.

David Corden as the loud, uncouth cockney – the complete antithesis of Nicholas Lumley's character – gives an excellent comic performance full of coarseness and ignorance – the perfect sandpaper to rub against the other's carefully preserved and precious personality.

The two wives are beautifully played by Kerry Stockwell and Julia Savill. Stockwell is strong and forceful, yet yearns for a better life; Savill is all fuss and hot air. They complement the male characters perfectly. But it is Mardell's script that is the star. The dialogue crackles, the plot is skilfully crafted and the characters are completely authentic and believable.

This play calls out to be staged in front of a larger audience. Theatres at the moment seem to be full of revivals or works that are set to a tried-and-trusted formula; while there may be similarities to Ayckbourn's ouevre here, Mardell is a unique talent.

To 17 Feb (020-7793 9193)

Arthur Rowland, teacher, Wiltshire