Government Code and Cypher School: Signals Intelligence Passed to the Prime Minister, Messages and Correspondence

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: 10th Air Corps reports on April 5 air recces over Cairo, Alexandria, and Sidi Barrani, raids on Tobruk, heavy RAF activity, and attacks on Derna, Gambut and Gazala; that the German Air Force (GAF) in Africa are instructed to give priority to attacking British airfields on April 4; the 10th Air Corps reports the result of photographic reconnaissance of Alexandria, on April 5; that no heavy fighters are serviceable in North Africa on April 5, and that Crete is requested to provide escorts for air transports from Crete to Derna; that German forces are attempting to counter the British thrust from Tengeder to Hamarin, on April 4; on German arrangements for the standardisation of air reconnaissance between Africa and Crete, and along the African coast; that Piraeus harbour is closed as a result of an RAF raid, on April 5; on the 4th Air Fleet's intentions for April 4-5, including the destruction of bridges over the Donetz; and a 5th Air Fleet estimate of the position of a Murmansk-bound convoy, on April 5.