During the Second World War the Germans used two kinds of high-grade cryptographic system: Enigma, and what we called ‘Fish’. There were two forms of Fish. The official name for one was the Schlüsselzusatz (cipher attachment) SZ40 and 42, made by Lorenz, and which we called ‘Tunny’. The other was the Siemens T52, which we called ‘Sturgeon’. I worked on Enigma and on Tunny. After the outbreak of war I had to wait more than a year before I obtained suitable war work. My personality is not that of an officer and a gentleman, rather that of a philosopher and a mathematician, so I was not expected to join the army, other than, later on, the Home Guard. (On my first day in the Home Guard I was taught how to throw a hand grenade, although in years of compulsory cricket I was never taught how to bowl!) Eventually I was interviewed by the twice British chess champion Hugh Alexander, and the Cambridge mathematician Gordon Welchman. I knew Alexander in the chess world. I had another job offer which, unknown to me, would probably have involved work on radar. I chose Bletchley Park which I thought would be somewhat romantic. A few weeks before I joined Bletchley Park, when I was playing in a chess match where the chess master Stuart Milner-Barry, later knighted, was playing, probably on the top board, I was tactless enough to ask him whether he was working on German ciphers. He replied, ‘No, my address is Room 47, Foreign Office.’ Shortly thereafter, when I joined BP, he was there, sure enough working on German ciphers! At first the official address at Bletchley Park was indeed Room 47, Foreign Office, Whitehall, London, but soon it became permissible to give one’s private Bletchley address. I joined BP on 27 May 1941, the day the Bismarck was sunk, and was met at Bletchley railway station by Hugh Alexander. As we walked across a field, on the way to the office, Hut 8, he told me the exciting news that we were just beginning to read the German naval cipher system (which used the Enigma). I shall never forget that sensational conversation.
Eye trackers in evaluation of transformation of historical monuments. Revitalisation of the Dresden arsenal