A new book written by Alan Turing's nephew, Dermot, is out now and titled X,Y, & Z (signifying the French, British, and Polish codebreakers). The author was interviewed on Radio 4's Today programme this morning. His main point was that the Poles should be given far more credit for their work in breaking Enigma than they have been hitherto. Well, point taken I guess, though I have always understood that they invented the techniques, especially the 'Bombas' that reverse engineered the military Enigma rotors, and that Turing simply refined further.
What is new to me though is that far from disappearing after the defeat of Poland, the Polish team escaped to work together as decoders with the French Resistance in Southern France and Algeria, rather than their military counterparts who ended up with the British. Presumably the British knew about this and the extraordinary security threat it posed. Churchill's geese that laid his Golden Eggs could be exposed at any time by German Counter Intelligence in its own back yard. It seems we were luckier than we ever imagined that the secrets of Station X remained just that.
https://www.nature.com/articles/d41586-018-06149-y