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 reports: that the Hipper, Prinz Eugen and Scheer are with the 5th Destroyer Flotilla as escort on stand by, on May 1; and that the Admiral commanding the northern waters was ordered to attack an Allied convoy, on May 1.