It seems an odd sign of the times that the fringe should be most interesting these days when excavating the past, as if ticking the boxes in the repertoire left blank by the National Theatre and the unadventurous regional reps.
Here's another fascinating play that characterises the "lost" transition period between the Edwardian and post-war modern theatre, written by G.B. Stern, a well-known lady novelist of the 1920s and 1930s who was much admired by Noël Coward (and referred to by him as "Peter Stern" in his Diaries).
As the programme note tells us, Gladys Bronwyn Stern (1890-1973) also trained as an actress, like other forgotten female playwrights Clemence Dane and Dodie Smith.
The Man Who Pays the Piper (1931) follows on women winning the vote in 1928 as a fashion house director, Daryll Fairley (Deirdre Mullins), makes her way in a man's business world while balancing private duties as head of the family.
In a prologue set in 1913, we see 18 year-old Daryll being torn off a strip by her father (Christopher Ravenscroft), a doctor; she's been out dancing and comes home way after midnight.
Thirteen years later, with her father dead (in the war) and mother (Julia Watson) re-married - with her permission - to an impecunious musician (Stuart Fox), Daryll has to deliver a similar lecture to younger sister Fay (Emily Tucker) who turns up in Holland Park in the small hours with a bunch of raucous young revellers.
There is lots of wonderful detail surrounding Daryll's assumption of responsibility (she's the eldest of six): a much discussed visit to No, No Nanette (the hit show of 1925), a fearsome telephone stand-off with the water authorities (they've "bungled" the gas circulator, and there's no hot water), mother's sudden acquisition of an inheritance from an "admirer" she's visited once a week for years.
But Helen Leblique's initially spring-heeled, beautifully costumed production gets a little bogged down in the middle, as a lot of the exposition becomes turgid and the writing rather flat.
A jolly good edit is needed, but the actors gamely rise above the plodding progress, especially Mullins as Daryll, a marvellous study in steely Thatcherite determination flawed with emotional vulnerability and a sense of history changing around her.
Finally, we're in an art deco flat in Knightsbridge in 1930 (the year of Coward's Private Lives) as Daryll and husband Rufus (played with perfect period profile by Simon Harrison), attended by a resurrected Ravenscroft as a gloriously deferential old butler, hammer out a new format for a modern marriage.
In a brilliant last scene, the door seems to open on a new era, and the play ends on a breathtaking semi-colon.