The programme quotes R. D. Laing on Jill, a distorting mirror to herself, who has to distort herself to appear undistorted to herself. You can make any number of such games from Twelfth Night "You do think you know not what you are," says Viola to Olivia. "If I think so," says Olivia, "I think the same of you." "Then think you right, I am not what I am," Viola confesses. But it's no more than a game; as an identical twin, I've experienced enough mistaken-identity complexes to recognise the results in others, real or fictional.

If Peter Gill in his production for the RSC has worried too much about such things, at least it doesn't show in the play, which emerges as no more than the familiar black-edged comedy, in which the mistaken identities are exaggerated by Shakespeare's use of boy actors as girls and of girls posing as boys. Short of deliberate eccentricity, in fact, nothing need be added to the instant mix but talent, and that is amply available here.

Jane Lapotaire makes a very boyish boy, though I have to say that at her first entrance, when she was still a girl, she drove me mad by her continual breathless trotting round the stage when she was supposed to have just come ashore from a shipwreck; nor do I think she should be quite so ready with her fists. Robert Lloyd as Sebastian duplicates her prettily.

The weight, as usual, swings in the direction of Malvolio, to which Nicol Williamson brings all his individual talents. This is a tall, crane-like steward, moving with the stiff efficiency of a well-programmed robot and speaking in haughty tones from which the native Welsh is being carefully squeezed. (It returns in full flood when the unhappy man is tied up in the cellar and all his dignity is gone.) Perhaps Mr. Williamson having had such a success with it in Coriolanus, is over-generous with his long Pinteresque pauses, but he can move a house to heartbreak at a stroke, and duly does so by his delivery of his final un-forgiving words through the hands with which he is covering his face in name.

David Waller is a tough old Toby, perhaps a retired colonel in the Illyrian cavalry, and Frank Thornton, an Ague-cheek rather more unambitious than we have grown used to. Neither John Price's Orsino nor Mary Rutherford's Olivia is much more than handsome; the director seems purposely to have kept them in low profile, as the politicians say, to retain the more important characters in the limelight.

William Dudley's set is little more than a square box with a mural of Narcissus on the back wall and graffiti framing the front arch. (They read: "O learn to read what silent love hath writ" and "O know sweet love, I always write of you.") Orsino's court spends much time lying on cushions on the floor caressing one another, but if Orsino is meant to be gay, as the text may be taken to suggest if necessary, how is it that he spends so much time and passion courting Olivia?

The music that feeds his love is a Bohemian-sounding romance played on the violin. Surely it should have been a viola?