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 Russian Front: that the latest Russian penetration is considered a serious threat to supply-shipping traffic to the Crimea, on March 8; on South-east Europe: an appreciation by the Ground Officer Commanding (GOC) the 15th Mountain Corps, on February 26; and Naval Headlines.