The Mousetrap opened in London in 1952. Agatha Christie’s murder mystery began its London West End run at the Ambassadors Theatre on 25 November that year.
Strictly speaking, the play premiered earlier, on 6 October 1952, at the Theatre Royal in Nottingham. That distinction can cause confusion, but both events occurred in 1952, so the stored answer is the canonical year for a question asking when the play opened in London.
The production became famous for its twist ending and for the tradition of asking audiences not to reveal the solution. Richard Attenborough played the original Detective Sergeant Trotter, while Sheila Sim was the first Mollie Ralston, owner of Monkswell Manor guesthouse.
The play is renowned as the world’s longest-running stage production. It ran continuously in London until performances were suspended during the COVID-19 pandemic in March 2020, then reopened in May 2021. In 2025, it reached its 30,000th performance, an extraordinary achievement for a stage mystery.