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 report on West Europe: that the German Air Force (GAF) are to begin operations against the Allied invasion fleet with large (FX) rather than smaller (HS) radio-controlled bombs, on June 14; and a comment by the Assistant Chief of Air Staff Intelligence (ACASI) on FX and HS bombs and GAF expertise, dated June 16.