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 on the Caspian Sea: of German preparations for a naval force, on September 27; this file also includes a message from the Prime Minister (PM) to C, thinking of sending a personal message about this to Stalin, on September 30 (a faint note on the coversheet appears to indicate that the PM notified Stalin on [October] 1).