Christopher Gray enjoys a convincing portrayal of the iconic detective Hercule Poirot

Agatha Christie’s verdict on her first play, Black Coffee, dating from 1930, is one that can usefully be borrowed by a critic in search of accuracy and brevity in his appraisal. “Although full of clichés,” she stated, “it was not, I think, at all bad.”

In truth, it is rather to be thought almost all good. This is especially the case when it is presented with the polish, the telling period detail and the ready wit — a quality by no means lost on the Queen of Crime — that the Agatha Christie Theatre Company supplies under director Joe Harmston.

Having toured since 2006, the officially approved outfit now brings to the stage at last Dame Agatha’s most famous creation, the elaborately moustached Belgian detective Hercule Poirot.

This is the only one of her plays in which he appears and was written in order to achieve a more accurate picture of the character than had been offered in adaptations of her novels by other hands.

Jason Durr, late of ITV’s long-running nostalgia-fest Heartbeat, gives a relishable portrait of the sleuth, required here to investigate the murder of noted scientist and the theft of his formula for an atom bomb.

To a comical, Clouseau-esque mangling of the language (Poirot has not quite, as he laughably thinks, ‘got’ our English), Durr adds much excellent business of eyes rolled, hands delicately fluttered and shoulders shrugged to convey the pernickety prissiness of this amiable seeker after truth.

As so often, he is assisted — if this is the mot juste — by the unflappable true-Brit Captain Hastings (Robin McCallum) and later by that pillar of the constabulary Inspector Japp who, after spotting a wrong tree, never fails to bark up it. Eric Carte gives a well-judged comic turn in the role, having already shown us, in the deceased scientist, Sir Claud Amory, a snooty man almost as vain as Poirot.

The range of his possible killers is satisfyingly wide, with the usual Christie touch of keeping it mainly in the family.

So besides his secretary Edward Raynor (Oliver Mellor), there’s his Queen Mary lookalike sister Caroline (Deborah Grant), his debt-ridden son Richard (Ben Nealon) and a tasty flapper niece (Felicity Houlbrooke) whose ‘fast’ taste for cocktails and the like contributes to the authentic Twenties’ flavour already achieved in designer Simon Scullion’s art deco Amory library.

Richard’s lovely wife Lucia (Georgina Leonidas) has to be in the frame, too, being half Italian, while her sinister connection Dr Carelli (Gary Mavers) — a fully-fledged foreigner, as is often observed with distaste — is as good as guilty from the start.

Christie aficionados might be amused to note the mention of spider’s webs and a mousetrap, both later to figure prominently in her playwriting career.

Black Coffee
Oxford Playhouse
Until Saturday
Tickets: 01865 305305