So you think you know who played the most memorable and engaging British screen sleuth. Basil Rathbone as Sherlock Holmes? Margaret Rutherford as Miss Marple? Dear chap, you obviously overlooked Exhibit A, at last available on video: Alastair Sim as Inspector Cockrill of Scotland Yard.

It’s a crime that Sim played the wickedly manipulative Cockrill only in Green for Danger (there were no sequels). But the pleasures of his portrayal are easily prolonged on cassette: As Sim works to unmask a murderer among the staff of a World War II hospital, half the fun lies in pausing the tape to savor radical shifts in his grasp of the suspects’ motivations.

Literal bombshells, in the form of German air attacks, spur the action along, and director-cowriter Sidney Gilliat uses these ”doodlebug” bomb raids to create terror (an injured postman sets the plot going), humor (in Sim’s sprawling dives for cover), and an ingenious red herring. You’ll have to look hard to make out faces in the tape’s dim-looking night scenes, but hang on for the Hitchcockian finale in which well-intentioned doctors and the police wind up mangling the person they set out to save.