Kenneth Branagh, like his Poirot, cares about cutlery. The director and detective’s fastidiousness both find their ideal home on the Orient Express, where waiters measure fork placement with the precision of Poirot’s sacred monster of a moustache.

Some site-specific theatre feels like a really good fit. You could say, in this case, that it seems like poetic justice.

A year ago to the day the BBC laid on a festive slaughter of Agatha Christie characters. And Then There Were None had the look of a well-dressed abattoir as her victims toppled like ninepins at the hands of an invisible slayer. The scriptwriter Sarah Phelps has returned to the queen of crime for this year’s two-part Christmas murder mystery. The source for The Witness for the Prosecution is a mere 23-page story in which there’s really only house room for one corpse.

None, or two? Only the tiniest whiff of spoiler is involved in pointing out that while the stage version, or at least the one I saw with an actor friend playing an early victim, settled for a semi-happy ending, this magnificently brooding adaptation in three parts – just the right length, surely – dooms us to ultimate discomfort, as an especially merciless Agatha Christie intended.

Inevitably, an aura of fin-de-siècle gloom hung heavily over this final Poirot. So daunting was the prospect of terminating his 25-year career-defining stint as Belgium's finest (albeit imaginary) export that David Suchet insisted on shooting the last one before the others in the concluding series.

In recent times, the Middle Ages have been ghettoised on those channels you watch in pubs. Game of Thrones, and anything by Regius Professor of bunkum Ken Follett, are history laid on for people who don’t give a toss about history. You know, the snorey stuff about canon law and tithe barns. For those who prefer their medieval high jinks only semi-faked, The White Queen prances into one’s purview on a white liveried steed. Its aim is to show a clean pair of hooves to all that oikish pillaging and plotting which have lately steamed up the nation’s undergarments.

Crime fiction once lured you in with lurid covers acting like a B-movie poster or fairground barker, selling the promise of thrills within. The British Library’s new exhibition is disappointingly light on such disreputable fare, and much too brief. But within its self-imposed limits it manages to indicate the genre’s range, and illuminate some forgotten corners.

A blackout, a snowstorm, a scream, and there you have it – the longest-running play of all time. The mystery of The Mousetrap is legendary, preserved by a code of silence that bonds all those who have performed and watched this classic whodunnit. Yet greater even than this is surely the enigma of how so generic, so unassuming a play should come to endure so persistently. Is it merely tradition that keeps Agatha Christie’s Mousetrap in business, or can this period piece really still have something fresh to say in its resolutely RP tones?

David Suchet has been perfecting his impersonation of Hercule Poirot for more than 20 years, perhaps sympathising with Tina Turner’s maxim, “The longer I do it, the better it gets.” The way Suchet keeps finding new little tics and eccentricities to keep the character fresh is a substantial feat, since around him, the fixtures and fittings of Agatha Christie-land have proved impregnable to change.

Miss Marple is frequently described as “a little old lady”, but for all that she casts a giant shadow. Just ask any new actress invited to portray this most beloved of characters. When you play the spinster sleuth, you have massive shoes to fill. That has certainly been Julia McKenzie’s experience