The idea that you don't need to achieve something to 'be someone' is the starting point of this offering from the ever splendid Alan Ayckbourn, now showing at The Oxford Playhouse. Charlie Conrad (Stephen Beckett) is a cheerful nitwit who has enjoyed seven years of fame as a celebrity underachiever. Married to the beautiful, deadpan, but wistful Linzi (Melanie Gutteridge), who has given up her own career to be a wife and mother, he seems to lead a charmed life: rich, successful, and adored by an undiscerning public. The cracks, of course, begin to show from the very first scene, as Linzi's dissatisfaction and Charlie's inadequacy become apparent, and the audience is all too painfully aware that the situation can only lead to trouble.

The story unfolds in a Victorian folly in the gardens of Charlie and Linzi's Georgian mansion. It's the symbol of their success, and ultimately of their failure; the scene of their crumbling marriage and of Charlie's professional suicide when caught in a compromising situation with a fan. The ongoing comedy also provides much of the pathos; the disparity of intellect between Charlie and Linzi is apparent in their every exchange, highlighted by his inability to remember the history of their house as she reels off names and dates with an utter lack of interest. More immediate humour is provided by the achingly polished and cynical lawyer Hugo de Préscourt, (Stuart Fox), and some of Charlie's idiotically naïve behaviour, especially when facing Gale Gilchrist (Alexandra Mathie), a female journalist with a savage reputation, leaves the audience chewing on its own fist with embarrassment.

This glimpse of the world of modern celebrity is seductively familiar, satirising the stuff of so much coffee-machine gossip, slyly holding back from revealing what Charlie and Linzi are actually famous for and leaving us to speculate on which particular celebrities are being sent up. The action is slick, the dialogue quick and witty, and the cast excellent, but the interplay between the characters was not always convincing. Part of the problem is that we're never quite sure what to think of Charlie. Is he a likeable ingenu caught out by events beyond his control, or a calculating realist (admittedly a pretty gormless one) out for the main chance? His occasional flashes of poignant, childlike insight seem to suggest the former, whilst his interaction with Gale Gilchrist hints at something a little darker. At any rate, it's difficult to see what the other characters are to make of him, and, as Charlie himself admits to being in some sense a 'non-character' only discernable by the peculiar behaviour of those around him, this makes for a few disturbing ripples in the smooth progression of the play.

It's a cheering thought that the concluding point of what is an immensely enjoyable play the might be the very opposite of its opening theme: you don't need to be someone to achieve something - but to an audience unconvinced by Charlie's conviction of finally having pulled off something extraordinary in the circular folly of his life, there's a suspicion that what we're seeing is just a series of pointless actions performed in a setting which is, by its very nature, pointless - that we're all people who ought to be home and dry but still find ourselves foundering in the water. Ouch, Mr Ayckbourn.