Henry Hewitt

Will Hay plays a Professor teaching at a correspondence school who discovers that a Nazi agent is trying to prevent a trade treaty being signed between England and South America. The agent is posing as an economics expert seconded to the trade delegation. The professor must find the real economist and expose the agent. (imdb)

A doctor enlists the help of a policeman in order to search for a blood donor with a rare blood type.

Three British sailors find they've accidentally strayed on board a Nazi ship during WWII. They then proceed to take it over and requisition it for the Royal Navy.

In the lead-up to the First World War, a French military attaché falls in love with the wife of a prominent German in Stamboul in the Ottoman Empire. (Wikipedia)