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 on the Russian Front: of German Air Force (GAF) air operations for December 4; of the 4 Air Fleet's operation intentions for December 4; a German report of December 4; that the GAF close support units are to move to Crimea, on December 4; that a flak unit is to be posted from Romania because of heavy Soviet air pressure, on December 4; and on the Russian fronts and Yugoslavia: a German report of December 4.