Garry Essendine, Noel Coward’s self-portrait in his wonderful war-time comedy of monstrous self-regard, is said to be advancing with every sign of reluctance into middle age. Simon Callow, as both himself and Garry, has obviously been romping in that state of comparative decrepitude since the age of about ten.

This in itself would not be a deterrent to playing Garry – it wasn’t for Donald Sinden – but another, more insuperable hurdle for Callow is Garry’s reputation as “one of the world’s most famous romantic comedians” for whom ladies happily lose their latchkeys and foist themselves on him in the small hours of the morning.

Callow is a character actor of considerable, not to say rugged, charm, but Garry is a superstar matinee idol, and there's a big groaning gap here that Michael Rudman’s efficient production and Callow’s indomitable performance have trouble bridging.

Where booming, barrel-chested Callow scores is in his wounded reaction to accusations of over-acting (“We stopped you in the nick of time from playing Peer Gynt”), or in his vein-bursting fury at the presumptions of the fledgling playwright Roland Maule (a very funny, hyper-active Robin Pearce), or in his confessions of unquenchable, tormenting vanity (“It’s agony watching myself go by”).

What Callow also brings, perhaps unwittingly, is an unscripted layer of self-delusion, so that Garry’s posturing is not only funny but also a little sad. He has surrounded himself with acolytes – notably Tilly Tremayne’s loyally resigned secretary and Richard Hollis’ matter-of-fact valet – and conducts his professional life, as did Coward, “for the good of the firm”. Callow’s attempts to preserve the status quo – exiting stealthily in homburg and dark glasses, or performing an over-elaborate mime – are the grotesque signals of an exhibitionist, not an actor.

Still, the bubble reputation is well sustained in Paul Farnsworth’s black and white art deco studio, furnished with an awkward spiral staircase, chaise longue, five pouffes and a piano. Photographs of Callow in action – from my Bath chair I could spot his Orlando, Mozart and Lord Foppington – clutter every surface, but the large centre-stage caricature is a hopelessly poor one. Maybe that's the point of it.

Garry’s wife (they are separated) is given a sharp, cutting edge by Jessica Turner, and Lysette Anthony is a seductively porcelain Joanna Lyppiatt, especially when draped on the sofa in green velvet. Marianne Oldham is suitably gormless as the pretty debutante who wants to be an actress, but I am incensed to see that the new anti-smoking tyranny has deprived Victoria Lennox’s insufficiently slovenly Miss Erikson of her drooping fag and hacking cough.

- Michael Coveney