Director Thorold Dickinson with Mervyn Johns, Nova Pilbeam, Jack Hawkins

Originally commissioned by the War Office but released commercially by Ealing Studios. Its message was the familiar “careless talk costs lives” one. Context was important: the knowledge that this was life and death stuff, that some of the actors had been given leave from the forces to make the film, and that it would have been watched by real wives, parents and siblings of people risking their lives in the armed forces. In other respects, it was a film that rattled along to its doomed conclusion (although successful as a destructive mission) and presented its crucial message very effectively. Mervyn Johns was perfectly cast as the unassuming little man who hears everything and passes it on to the Nazis: never overplaying his part but always there as a reminder to the wartime audience to be discreet. Interestingly being a blabbermouth crossed social lines: the upper-class officer and the regular private were each as foolish as each other, and the worst offender was a wing commmander.

Like “Went The Day Well?”, its occasional violence is quite shocking because it seemed so unexpected for a film of its time. It’s as if these films tried to jolt the British public into an acceptance that violence and brutality were a means of defence as well as aggression. I can only be glad that I’ve never been in a position to test that proposition.