Ambassadors Theatre opened on 5 June 1913 and was designed by W.G.R. Sprague, who also designed the St Martin’s Theatre located next door. The first production at the theatre was of Panthea, a play by Monckton Hoffe, which ran for only 15 nights. Britain’s longest running production, The Mousetrap by Agatha Christie, opened at The Ambassadors on 25 November 1952 and played there until its 21st Anniversary.
In 1996 the theatre was transformed into two studio spaces to accommodate the Royal Court Theatre Upstairs who were residents until 1999. After their successful residence, the theatre was converted back to its original design and renamed The New Ambassadors Theatre but reverted back to its previous name in 2007. The Ambassadors is currently home to Beginning , a new play by David Eldrige.