The poster promoting Quartet prominently parades a national critic’s opinion that its author Ronald Harwood is “unquestionably our greatest living playwright”. This seems rather to overlook the greater claims of his fellow knights of the page Tom Stoppard, David Hare and Peter Shaffer, not to mention those of another writer, Alan Bennett, known to have rejected the ‘K’ — twice. No matter. Harwood is a considerable craftsman, sure enough, and Quartet is a remarkably well-crafted, if undeniably slight, play.

Its focus is a group of one-time opera singers living out their last years in a retirement home in Kent operated — on somewhat authoritarian lines, one gathers — specifically for retired members of their profession. For some, it seems, an element of charity is involved, which probably accounts for the bossiness.

Initially, we meet three of them at their ease in the music room. There is the buttoned-up, intellectually inclined tenor Reginald (Michael Jayston), mugging up on Ernest Newman’s theories about Wagner. Contralto Cecily (Gwen Taylor), meanwhile, sits plugged into her iPod (or similar), mouthing the words of the arias she is listing to, and oblivious to the lubricious remarks aimed in her direction by the goatish old baritone Wilfred (Timothy West).

He admits to having sex on his mind almost all the time. He says he requested Viagra from a doctor who asked — West injects hilarious incredulity here — what he wanted it for. “What do you think I want it for?” Instead, he is offered “something to calm you down”.

A link between the trio is that many years earlier they had appeared together on a seminal, still-popular recording of the great Act III quartet from Rigoletto. Even as one ponders the unlikelihood of all three of them pitching up in the same home, still greater suspension of disbelief is required with the sudden arrival — suggesting the possibility of a reprise of that performance — of the fourth singer.

She is one-time soprano star Jean (Susannah York), still exhibiting many of the characteristics of behaviour — haughtiness, self-regard, bad temper — that have come to be considered trademarks of the prima donna. These have been slightly tempered, now, though, by the fact that she is down on her luck.

This is a peach of a part for Ms York, and we watch in fascination as it is plucked neatly by her well-manicured fingers. With such names as are involved in this production, the acting, under director Joe Harmston, was never going to be anything other than exemplary. Nor is it. Booking is highly recommended, despite occasional hiccups in the play’s plotting.

n Milton Keynes Theatre, until Saturday Telephone box office on 0844 8717652 — keynes. Oxford Playhouse, August 16-21. 01865 305305 — There will be an interview with Sir Ronald Harwood in Weekend next week.