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 Minister for Foreign Affairs to the ambassador in Hsinking, in China, that Japan is anxious to preserve Soviet neutrality, on May 11; from the Japanese minister in Berne, relaying advice from a German diplomat on Japan's future policy, on May 5; and from the Portuguese minister in Tokyo, giving Japanese views on the Okinawa battle, on May 6.