PERHAPS I’ve watched too much 24.

I became such a fan of the hit US drama, with its multiple twists and turns, that I started to second-guess what the weekly episode shocker would be.

And it means that I’m now frequently disappointed when the plot of most thrillers just aren’t convoluted enough. So it’s no surprise that I had the murderer sussed fairly early on in this legendary whodunit – on its first tour outside of the West End to mark its 60th anniversary – which famously has a twist at the end that audiences are asked not to reveal.

The set and scenario are typically Christie: wood-panelled drawing room with an open fire and snow falling outside the window as news comes through on the radio of a murderer on the loose. You almost expect Poirot to come waddling on.

Instead, we have some familiar faces from the world of soaps, as the owners of this country home turned guest house welcome their first arrivals over one snowed-in weekend.

In contrast to some dusty old Christie plays I’ve seen, this has a pace and lightness, with plenty laughs courtesy of Steven France’s camp guest Christopher Wren (whom I initially hoped would be the first victim, then grew to like) and hard-to-please Mrs Boyle (Elizabeth Power), while Karl Howman (Jacko from 80s series Brush Strokes) is unrecognisable as the mysterious Mr Paravicini.

Add fellow guests Major Metcalf (former Archers star Graham Seed) and tomboyish Miss Casewell (Clare Wilkie); plus Det Sgt Trotter (Bob Saul) and hosts Mollie and Giles Ralston (the wonderfully clipped-voiced Jemma Walker, and Bruno Langley) and there is enough in the mix to raise all kinds of suspicions about the identity of the killer in the midst.

By the second half I’d worked out two possible scenarios, one of which proved correct. That said, you couldn’t guess everything as there are lots of red herrings and “clues” that go nowhere.

With demand so great to see what is the world’s longest-running play, an extra matinee was added to this week’s run.

Take The Mousetrap for what it is – a now-legendary period piece – and, like me and the rest of the packed-out theatre on Monday night, you’re bound to enjoy it, even if you do see the plot twist coming.

At the end, the audience is politely asked to keep the secret and it really would be a crime to spoil the fun.