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: Naval Headlines; from the Japanese ambassador in Berlin, a report of April 19 on his visit via Salzburg to Berchtesgaden for talks with Hitler, Ribbentrop and Keitel, in particular discussing the situation in Russia; and a report of April 16 from Tokyo to the ambassador with observations made by the Japanese delegation that had just returned from Russia.