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 correspondence: a draft message to Brigadier Maclean on German operations to liquidate the partisans in Yugoslavia, with the Germans possessing a highly placed source in Tito's HQ and Yugoslav nationals working for German intelligence, on March 9; and a note from the Director of Military Intelligence (DMI) to C advising him not to transmit the contents of the report to Brigadier Maclean; and on South-east Europe: a report on details of German phases of an operation to annihilate the guerrillas in Yugoslavia, on March 1.