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 contains a message from C to Mr Loxley, giving summaries of signals from von Papen to Germany on pressure put on Turkey during the Cairo Conference; and a German intelligence report of a secret treaty between the Allies and Turkey permitting the transit of submarines through the Straits.