Government Code and Cypher School: Signals Intelligence Passed to the Prime Minister, Messages and Correspondence

A file of signals intelligence reports, messages, and correspondence issued by the Government Code and Cypher School and sent by the head ('C') of the Secret Intelligence Service (MI6) to the Prime Minister, Winston Churchill. This file includes the following report on West/East Europe: that the Captain of U-boats gives instructions for an attack on the next PQ-convoy to the Soviet Union, on April 20; a query from the Prime Minister (PM) to the First Sea Lord (1SL); and 1SL's reply, on April 21.