AllMovie

The San Demetrio is a British Merchant Marine vessel, traversing the Atlantic shipping channels in early 1940. The ship is disabled at sea, and thus left at the mercy of marauding Axis U-boats. The courageous crew manages to keep the San Demetrio afloat and guide it out of harm's way. San Demetrio, London is stylistically linked to the jingoistic "England Can Take It!" efforts of the wartime years. Despite its most ludicrous passages, the film is firmly based on fact (or at least the facts as related by author F. Tennyson Jesse).