THERE'S a fair spattering of well-kent faces (Blackadder's Baldrick and Time Team host Tony Robinson, Christopher Timothy from All Creatures Great and Small) in Mobil Touring Theatre's production of Alan Bennett's first stage play - and not surprisingly, given Bennett's talent for well-turned one-liners and richly eccentric, quintessentially English characters.

Indeed, the celebrity sprinkled cast miss no opportunity to ham it up in a succession of period cameos, Robinson, in particular, revelling in the chance to milk the piece's comic potential.

But while Bennett's messy early work might offer plenty of wry chuckles, acutely observed detail, and even show signs of the emergent talent of the writer destined to become an English National Treasure, it remains a clumsily-structured, unsubtle, and, ultimately, untheatrical piece.

Forty Years On draws on Bennett's experiences as a schoolteacher, set, as it is, in a second division public school on the occasion of the retiral of the faded, fusty, and deeply conservative old headmaster.

Bennett uses the device of a play within a play: the boys and masters of Albion House, under the direction of the incoming, and contrastingly liberal, Head, enact a kind of warts-and-all historical pagaent, featuring selected events and characters from the decades surrounding two world wars.

His intention - to reflect on changing values, the loss of a peculiarly English way of life, and the gulf separating the old stiff upper lip values and the new sensitive liberalism - is clear, but never, in this production, achieves any real sense of the pathos or nostalgia accompanying such shifts. Given no help from an inappropriately mechanised set and pedestrian direction, even Bennett's finely-tuned ear for dialogue fails to engage.