As the lights dim and the audience hushes, we hear melodramatic voices pertaining to the (gasp!) murder of a woman in London. A wireless broadcast, homage to the play’s radio origins, gives us the details and, as the curtain rises on the decadent mid-winter guesthouse interior, we are told to be looking out for a man wearing a long coat, light scarf and felt hat at the precise moment co-owner Giles Ralston (Timothy Dewberry) appears in just such an outfit.  With his nervously energetic dithering and the rich, plummy tones of his wife Mollie (Georgina Sutcliffe), it is all terribly British and a sure hit with the tourists, but the first half dithers a bit too much for my liking. There are some character subtleties, but on the whole, with such two-dimensional potential suspects, the pace is too slow to sustain a build up towards the point we’ve all been waiting for: another murder.

Like a game of Cluedo, each person is presented with a motive, an opportunity and few odd personality traits. It is difficult to assess the quality of acting when the characters are meant to be acting suspiciously, like Mr Paravicini (Neil Salvage) who, providing some creepy comic relief, comes across like a Welsh-Italian Bond villain. Having been parodied by plays like Stoppard’s Real Inspector Hound, it’s hard to know whether this is a parody of itself. There is enough ham on stage to open a butcher’s but somehow it doesn’t translate to an abundance of tension, comedy or edge-of-seat thrills. Each performance does exactly what is required of the part but the series of slow, expositional stories bogs down the progress somewhat.  There are some upbeat performances from Richard Keightley as Christopher Wren who embraces the quirky energy of a nervous young man with a troubled past. Even the Sergeant (Marcel Bruneau) injected some much-needed drive to the proceedings, doing well to maintain focus despite a mobile phone in the auditorium blurting out Bruno Mars on more than one occasion. We may not have guessed the murderer by then, but we certainly knew who the next victim should be.

Cut off from the outside world by a blizzard, the well-furnished set with solid oak doors, fireplace, cosy lighting and leaded windows which swing in the breeze is very atmospheric and, with some well-placed snow on the costumes, leaves little to the imagination. Some thought for the cheap seats would have been nice though, as the view through the window is clearly an interior wall with a curtain and a very snow-free floor.  Joining the others as guests for the night, Mrs Boyle (Jan Waters) is a wonderfully unpleasant lady with opinions (generally negative) on everything and Major Metcalf (Barry Aird) who is surprisingly naturalistic, given that his pipe-smoking war veteran could be as much a caricature as Paravicini. Both have some good comic timing and balance the exuberance of the younger characters well. Lottie Latham is wonderful fun as the tomboyish Miss Casewell though, like a lot of characters, is difficult to believe in her more emotive moments as she opts for a more melodramatic approach.  Obviously, you can’t have too many people seeming genuine to give the audience a fighting chance of guessing "whodunnit", but it felt a little like being spoon-fed at times.

The clues are there to deduce the murderer, though in true Christie fashion there are clues for everyone and, when the criminal is finally discovered, a hefty intake of breath went round the audience. There were plenty of people having a jolly old time of it but no matter how much snow and wind there was on the set, the heat in the upper circle wasn’t helping me stay awake. This is Agatha Christie by the numbers and I would say that anyone who enjoys sitting down to Midsomer Murders of an evening would be in their element. There aren’t as many laughs as The 39 Steps or as many jumps as The Woman in Black, but it is a good piece of entertainment that is very much part of our culture. Once I'd overcome the excitement of the mystery, I left feeling otherwise underwhelmed and perhaps the hype of this record-breaking show was too great, but there is still much to enjoy and if you’ve never seen it before, it’s worth it just to be part of the conspiracy.

The Mousetrap, at St Martins TheatreTom Oakley reviews The Mousetrap at St Martin's Theatre.3