The Queen's Keys - Paperback

A professor becomes a reluctant spy and his assignments help explain many of the historical oddities of World War Two, including the Nazi failure at Dunkirk, the end of the Blitz and the invasion of Russia.
Recruited by Churchill prior to the war, Professor Christoph Schroeder is tasked to find keys given to the daughters of Queen Victoria when they married into various European noble families.
The keys open a hidden safe which holds items that help alter the course of the war.
The Queen's Keys is an imaginative alternate history of World War Two.