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. The file includes the following correspondence: a letter from the Japanese ambassador in Berlin on the outbreak of the Japanese-U.S. war on December 8; instructions from Tokyo to Berlin on a proposed three-power pact on December 7; messages from the Japanese ambassador in Berlin forwarding a draft of the three-power pact provided by Ribbentrop on December 5; instructions to the Japanese ambassador in Rome to keep details of the Japan-Germany agreement from the Italians on December 2; a note from Tokyo to the ambassador in Berlin on unacceptable U.S. demands in their negotiations from November 30; a report from the Japanese ambassador in Rome on an interview with Mussolini on U.S. attitudes and Italian assistance to Japan in the war, from December 3; and on Italian readiness to sign the Three Power Pact on December 5; and instructions from Tokyo to ambassadors in Berlin and Rome on plans in the event of a break down of Japanese-U.S. talks on November 24.