An original poster for The Mousetrap

The Mousetrap started out as a 30-minute play called Three Blind Mice, written by Christie for Queen Mary's 80th birthday in 1947, before it was made a full-length show.

Richard Attenborough and Sheila Sim were the original leads when it opened at the Ambassador Theatre and notices said the play had a "fair degree of success".

Bemused

In 1958 The Mousetrap became the longest running British show before breaking the world record in the mid-1970s.

Christie herself seemed a bit bemused by its appeal.

Agatha Christie was surprised by show's success

"It's not really frightening. It's not really horrible. It's not really a farce. But it has a little of all these things and perhaps that satisfies a lot of people," she once said.

The show transferred to its current location at St Martin's in 1974.

Almost 300 actors have performed the play with David Raven making the Guinness Book of Records as "most durable actor" for 4,575 performances as Major Metcalf.

Nancy Seabrooke was understudy for the role of Mrs Boyle for 6,240 performances, appearing just 72 times.

Consistent

The original script has seen few changes over the years, the only alterations have been the deletion of references to rationing and identity cards which were in force at the time it was written.

Despite the changing cast over the years, the company has not missed a single performance.

In 2000, the set was replaced for the first time since it opened, but the same design was kept.

Only a leather chair and the mantle clock have appeared in every show since 1952.