Mamet's status as a major American playwright stands firm, but Sexual Perversity should never have been much more than a series of tentative sketches for an American Seventies TV soap opera. Thirty years ago when the sexual revolution was still in its nappies, free contraception remained a novelty and women's liberationists were in the first flush of freedom Mamet's quartet of would-be fornicators may have looked daring. It is different now. Director Lindsay Posner has hit upon an enraging idea of how to present Mamet's brief, film-like scenes. Instead of using a bare playing-area with a composite set, designer Jeremy Herbert uses stage shutters, with on-stage recesses serving as performance spaces. A curtain of photo-montages comes down between every scene, often for far too long, breaking any continuity achieved.