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: SHARK, that U-boat cipher keys for April 11 and 13 have been broken; on North Africa: that Italian destroyers are carrying 600 troops to Tunisia, on April 16; on the Mediterranean: that Kesselring orders the German Air Force (GAF) at Sardinia to use all its resources to construct blast bays within 3 days, from April 16; and that GAF Sardinia report the sabotage of cables, on April 16; from the Chinese minister in Ankara, relaying Turkish information on a Hitler-Mussolini conference, on April 14; and from the Portuguese ambassador in London, describing a lunch with Churchill, on April 14; 116535 was sent to the Chief of the Imperial General Staff (CIGS) (see 3015).