Robin LeFevre's cannily understated production, which I saw at a preview, tantalises with its air of tight-fisted tensions. The concealed truth is about to be forced into the open. When the play concertinas back to 1960's and the two men play their fathers, with Elizabeth McGovern's Nan completing the emotional triangle as her own mother, you come to understand how the sexual and emotional patterns of the next generation have been set.

The force of Colin Firth's remarkable acting transcends the mere erotic appeal that on television made him the fantasy play-thing of so many women. He portrays two men who loiter on the fringes of life, brooding over how to find the key to happiness. Firth's valiantly worn dejection always rings true. Dowdily dressed in despondency, an almost thread-bare charm and a long, grey-green pull-over as Walker, and then in the role of his bespectacled, stammering and introverted father, the less brilliant architect, Firth illuminates both men's diffidence and pain. Miss McGovern wears a vibrant sexiness, but remains enigmatically buttoned up. David Morrissey's Pip most powerfully shows how we may speak the most painful home truths in the mildest tones.