Coward wrote that he conceived the idea for the play while in Paris shortly after the Liberation and end of Nazi occupation. He wrote, "The city itself seemed to be unchanging, physically at least untouched by the horrors of enemy occupation. It didn't take me long however to realise that, behind the facade, a great deal had changed; the sense of immediate relief had faded, and there was an atmosphere of subtle disintegration, lassitude and above all suspicion". This led him to wonder "what would have happened to London and England if, in 1940, the Germans had successfully invaded and occupied us, which they so very nearly did". He decided to place the entire action of the play in the bar-parlour of a London pub, as "the most easily manageable meeting-ground for various types of Londoners".