Three blind mice, see how they run – and they have run and run and run for an incredible 62 years. Three Blind Mice was the title of the original 30-minute radio play that became The Mousetrap legend.

So what is it that keeps this whodunnit breaking and creating records? I first saw it at The Ambassadors Theatre, London, its home for 22 years, when it was already a phenomenon. In the intervening decades I forgot whodunnit. Would it now seem horribly dated? Had the producers tried to drag into the 21st century? No and no. It is an unfussy production which lets the drama, and melodrama, work for itself.

Of course it is dated. It is set in the late 1940s. But the style and the characters are true to their era. Although a great fan of Miss Christie’s mysteries, I never regarded her as a particularly good creator of three-dimensional personalities. They lack warmth and it is difficult to empathise with any of them. But they are colourful hooks on which the author hangs clues to the central puzzle. This cast keeps us on tenterhooks to the surprising end.

It is a still a darned good puzzle. A woman with a murky past has been murdered in London. Somewhere in the countryside about 30 miles away, a motley selection of individuals arrives at a newly opened guest house.

Of course, there is a snowstorm which traps everyone in the house. With the help of the obligatory dogged policeman, connections to the London murder victim are hypothesised and the avid detective fiction fan will think they have the villain sussed. But I bet you haven’t.