Catalogue description British supervision of Polish (London Government in exile and associated military and...

British supervision of Polish (London Government in exile and associated military and secret service) radio communications, including interception and code-breaking by GC&CS.

20/5/1944 C/6538 Foreign Office interest in the contents of W/T messages to Polish underground movement. 1/7/1945 samples of decodes of Polish military attache cipher messages. 3/11/1944 Probability that Germans are reading Polish traffic between Istanbul and London. 1/12/1944 Foreign Office require censorship of Polish communications to prevent despatch of messages to Russian-occupied Poland and to moderate propagation of anti-Russian feeling. 8/12/1944 Record of meeting to consider how Polish wireless communications to and from Poland can be controlled. 16/12/1944 Detail of Polish wireless communications. 22/12/1944 New instructions issued by Prime Minister, Foreign Secretary, Minister of Economic Warfare among others on censorship of Polish communications.

26/1/1945 Foreign Office most anxious that censorship of which the Polish Ambassador has been warned should be applied as strictly as possible. 6/2/1945 Foreign Office to Foreign Secretary."Present [Polish] Government oppose whole basis of settlement for which you are working and Poles with whom they are communicating remain underground...Propose to hold up all further messages from Polish Government pending your reply". 5/10/1945 Polish decodes by the Germans: 1944. 10/10/1945 Polish [Communist] Government cypher messages and an unauthorised radio transmitter in the Polish Embassy, London. 24/10/1945 Paper on the vulnerability to the Germans of Polish cyphers during the war. 15/11/1945 Polish clandestine radio network XR/3700

26/1/1946 Situation regarding the London Poles W/T network.