Behind the scenes on 'The Mousetrap'

As Agatha Christie’s classic whodunnit marks an incredible 30,000 performances, we go behind the scenes to find out what’s kept audiences coming back more than 70 years after its debut.

Imagine the London of November 1952: Queen Elizabeth is less than a year into her reign, Winston Churchill is the Prime Minister and BBC is the only broadcaster on TV.

One monarch, 16 PMs and hundreds of TV channels later, the world has changed in too many ways to count. Yet, at least one thing has remained stable over the last 72 years – the immovable presence of The Mousetrap, Agatha Christie’s seminal whodunnit, in the West End.

Originally commissioned as a radio play to mark Queen Mary’s birthday, the two-act thriller has dazzled millions of audience members from around the world with its tale of mystery and murder amid a snowstorm. As early as 1957, The Mousetrap became the UK’s longest-running play, and remains the longest-running play in the world. Outside of its 14-month closure during the Covid pandemic, the show hasn’t stopped running since it opened, not even breaking its streak when it moved theatres in 1974.

In March 2025, the play will hit another milestone with its 30,000th performance. Visiting the set ahead of a matinee performance a few weeks prior, there’s a feeling of calm in the air that surely comes from a well-integrated and well-rehearsed cast and crew. Company stage manager Paula Salmon has worked at The Mousetrap for nearly three years, and though a short stint compared to the show’s run as a whole, it’s been more than enough time to soak in the unique benefits of being part of such a theatrical institution.

“Because The Mousetrap has been running for 72 years, you get people that go, ‘I came with my grandma when I was a kid, and now I’m here with my granddaughter,’” she notes. “It’s amazing, and you can’t get that anywhere else. Some of the long-running musicals might have been running for 30-plus years, but it’s a whole lifetime we have here.”

The show surrounds the curious killing of a local woman, with each one of the visitors at Monkswell Manor guesthouse a suspect. Two of the possible murderers include the crotchety Mrs Boyle and fidgety young man Christopher Wren, currently played by Rekha John-Cheriyan and Richard Leeming respectively. With three matinees and six evening shows a week, the actors give their all to each performance.

However, before there’s time to risk burning out, the show is recast every six months, with all new actors taking over the roles.

“That’s what keeps the show fresh,” John-Cheriyan says. “Everyone’s enjoying themselves, giving their all and then after six months there’s another cast coming in with their interpretation. It’s lovely.” For Leeming, part of the show’s longevity comes from this practice of moving the cast along, as well as Christie’s timeless writing: “The script is open to reinvention. So, new actors can bring something new and distinct to the parts. They can really stand as new takes.”

As the show is based in “the present” at its time of writing, it has transformed it into a period piece over time. The set’s design has stayed consistent, still evoking what the reception room of a 1950s guesthouse would have looked like. Seeing the set up close, it feels strikingly realistic – unsurprising, as many of the props and furniture pieces have been in place for decades.

“Nothing’s new, or made for The Mousetrap – much of this set is about 30 years old,” says Salmon. Some elements are even more vintage than that: on the mantelpiece stands a small clock that has been present since the very first performance. “It’s the oldest prop in the West End,” Salmon notes.

Though the set is largely static, that doesn’t mean it lacks excitement for the audience; part of The Mousetrap’s charm comes in its commitment to its classic methods of creating visual and sound effects. In lieu of remote controlled-trickery, for example, a window rattles open with the help of an unseen member of the stage crew pulling it open with a hooked stick. Simultaneously, another will operate the wind machine – a large barrel-like device that closely imitates the sound of gale force wind as the handle is wound in circles. Like the mantle clock, the wind machine has also been around from the very beginning.

Since the action is set during a snowstorm, visitors to Monkswell Manor enter from the outside with “snow” on their coats and hats. To make this happen, mere seconds before their stage entry, actors take a trip to the snow room – a small space behind stage right with a spinning pipe on the ceiling that ejects a snow-like substance. After 10 seconds in there myself, I emerge covered in the stuff – but it melts off gently after a few minutes, like real snow but without the cold temperature, or the risk of hazardous puddles.

While many other West End shows have come and gone, The Mousetrap has survived and shows no signs of letting up. Though they only started their run as Mrs Boyle and Christopher Wren in November, John-Cheriyan and Leeming only have until May before they pass the baton to the next cast. One hundred shows in at the time of our meeting, the sheen still hasn’t worn off for them.

“It’s a huge privilege, because it’s such an iconic show – everyone knows of it, even if they haven’t seen it,” says John-Cheriyan. “It’s just a joy, because the audiences genuinely love it, and they’re always different – one show they could be laughing really loudly, others are clearly listening hard and trying to figure out the mystery.”

How the audience will respond to the 30,000th performance is yet to be seen – but if more than 72 years is anything to go by, it’ll be another hit that further secures The Mousetrap’s place in theatre history.

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Photo credit: the cast of The Mousetrap and behind the scenes on the show. (Photos courtesy of production)

This article first appeared in the March 2025 issue of London Theatre Magazine.