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 contains a minute from C to the Assistant Chief of Air Staff Intelligence (ACASI) pointing out the Prime Minister's (PM's) comment to paragraph 4 of a report from the Japanese ambassador in Berlin (see 5359 for the ACASI's reply to the PM); from the Japanese ambassador in Berlin, forwarding information from German sources on abortive U.S. large-scale daylight air raids against Magdeburg and Dessau on January 11, the position on the Russian Front, Turkey's neutrality and the fact that the daily Allied air raids against the Pas de Calais area were obviously targeted against 'reprisal' V-1 installations although these had not been damaged any more than the submarine pens there; and a paper dated January 20, a copy for the PM, from the War Cabinet Chiefs of Staff Committee, proposing the establishment of a new Comsec authority at the Government Code and Cypher School (CSS) to counter the potential exploitation of British communications and cyphers.