Harwood's Quartet – recently made into a film directed by Dustin Hoffman – is something of a companion piece to what might be his best known drama, The Dresser.

In the latter play, an ageing actor-manager treads the Shakespearian boards until he pegs out in the dressing room. In Quartet, a group of former opera singers have at least survived into retirement which they are eking out in what seems essentially to be a pleasant-enough home for ex-members of their profession. Three of the residents, Reggie, Cissy and Wilf - ex soloists – have formed a cabal whose equilibrium is threatened by the arrival of Jean, an ex-diva who is also an ex-husband of Reggie.

Can the ensuing tensions be resolved and can Jean be persuaded to join the others in a performance of a quartet from Verdi’s Rigoletto? It would not be too much of a spoiler to provide the answers to those questions because Quartet is not exactly a suspense-filled drama, more of a whimsical and occasionally melancholic reflection on the ageing process and the different ways in which people come to terms with it.

The four characters in the play might be has-beens, but they were definite weres, so to speak. They all had genuinely successful careers as operatic soloists. In fact, their recently re-released recording of Rigoletto is selling fairly well and plays an interesting part in the final plot twist.

So this is a not a bittersweet comedy of self-delusion, although all of the quartet do have personal secrets and sadnesses that gradually trickle out during confessional scenes.

Stuart Davison plays Reggie, the most disciplined and intellectual of the quartet, given to musing on the nature of art. But he is also given to sudden, irrational rages – abrupt changes of mood at which the actor is highly adept.

Cissy, touchingly played by Lynne Whitaker, is flighty and friendly, rather less secure than the others and displaying some signs of dementia.

The much-married Jean was once a major operatic star. She is now fallen on hard times and needs a hip replacement but the actress playing her, Julie Root, manages to exude plenty of the glamour she once possessed.

John Cohen is the louche Wilf, whose sexist banter and goatish behaviour are something of a front – although not entirely. This character is perhaps the most convincing portrayal of someone who once occupied a world of performance in which sexual tensions ran high. With his mobile face and raffish manner, John Cohen provides most of the humour in a play that is essentially a comedy, although it has melancholy undercurrents.

The four highly accomplished actors are directed by Derek Smith in a very good production that concludes on Saturday, when there is also a matinee.