Sometimes a conversation breaks out ahead of a production and stays at the forefront of the mind during a performance. And so it was here.

In the run-up to this rewarding and richly acted revival of Ronald Harwood's enduring play about theatre - in which Ken Stott is "Sir", the ageing, grandiose thespian regaling wartime Britain with productions of Shakespeare, and Reece Shearsmith is his dresser - Harwood told me during an interview that, in his view, the current and increasingly common convention that sees women actors play male classical roles, such as Glenda Jackson's forthcoming return to the stage as King Lear, is not to be encouraged. Especially Lear, the monumental role that weighs so heavily on Harwood's Sir. Because Lear, Harwood says, requires a particularly masculine energy.

Many oppose this view, including David Aaronovitch who in the Times responded with a characteristically eloquent rebuttal that cited the many advantages - political and artistic - that can arise when a woman plays a man. And I don't disagree. Yet Aaronovitch didn't quite nail Harwood's point about masculine energy, which is made so effectively, and funnily, by Harwood's play.

Though first seen in 1984, The Dresser, inspired by the author's own experience working for Sir Donald Wolfit in the 1950s, is set during the Second World War and in the shadowy reaches of a provincial theatre's backstage.

Sir, an actor of the classical tradition, is having a form of nervous and physical breakdown. Can he muster the strength needed for another performance of Lear? Can he continue to not only brave Hitler's bombs by refusing to leave the stage during air raids, but also cope with the strain of carrying poor dead Cordelia, played by his big-boned and buxom wife (a game Harriet Thorpe)?

This becomes one of the funniest running jokes in an already funny and achingly poignant play about the actor's selfish and presumptuous reliance on his long-suffering loyal dresser Norman, played with pitch-perfect camp by Shearsmith.

In Sean Foley's beautifully paced production, which is given a spring in its step by Ben and Max Ringham's unexpectedly modern incidental score, Stott is terrific as the blustering, utterly self-obsessed great actor.

But the great acting here is Shearsmith's whose painfully neglected Norman evokes the kind of vulnerability that might one day kill a person.

The play is a marvellously well observed study on suppressed and unrequited love. But, with a light touch, it also makes the point that, among Lear's defining moments, is the lifting of his dead daughter.

Whether or not this is a challenge to be accepted by Jackson (now 80) remains to be seen. But, in any case, Jackson would probably do well to stay away from Harwood's play, and Harwood might want to steer clear of Jackson's Lear.