The Bletchley Park Codebreakers Read Free Page B

cryptanalysts between the wars.
    Polish military intelligence realized at the end of the 1920s that the attempt to break Enigma would require the recruitment of professional mathematicians (one of whom, Marian Rejewski, was to make the first major breakthrough in the attack on it). In the summer of 1938, Denniston finally reached a similar conclusion and began including a limited number of mathematicians among the ‘professor types’ who were being earmarked for Bletchley Park. Initially, however, the mathematicians were treated with considerable caution and some suspicion. The first mathematics graduate recruited by GC&CS, Peter Twinn of Brasenose College, Oxford, was told after he began work early in 1939, that ‘there had been some doubts about the wisdom of recruiting a mathematician as they were regarded as strange fellows,notoriously unpractical’. Twinn owed his recruitment, at least in part, to his postgraduate work in physics. Physicists, he was told, ‘might be expected to have at least some appreciation of the real world’ – unlike, it was believed, most mathematicians.
    Though the first wave of ‘professor types’ to arrive at Bletchley Park at the outbreak of war consisted chiefly of linguists, classicists and historians, it also included two brilliant Cambridge mathematicians: Turing from King’s and Gordon Welchman from Sidney Sussex College, who may originally have been earmarked because his mathematical brilliance was combined with skill at chess. According to the Cambridge Professor of Italian, E. R. ‘Vinca’ Vincent – probably the first ‘professor type’ to be selected – ‘Someone had had the excellent idea that of all people who might be good at an art that needs the patient consideration of endless permutations, chess players fitted the bill.’ Among other chess experts to arrive at Bletchley Park in the early months of the war were Hugh Alexander and Stuart Milner-Barry. Turing, Welchman, Alexander and Milner-Barry were jointly to sign the celebrated Trafalgar Day memorandum in 1941, which Churchill minuted, ‘Action This Day’. Whatever the original reasons for their recruitment, the first professional mathematicians at Bletchley Park made themselves indispensable so quickly that the recruiting drive was rapidly extended to mathematicians without a reputation as chess players.
    Though GC&CS operated on a very much larger scale after its wartime move to Bletchley Park than it had done between the wars, at least one aspect of its original organization remained both of crucial importance and considerably ahead of its time. Denniston considered the ‘official jealousy’ which had prevented any collaboration between naval and military cryptanalysts from October 1914 to the spring of 1917 ‘the most regrettable fact’ in the history of British wartime Sigint. The establishment of GC&CS in 1919 was intended to avoid any repetition of such interdepartmental feuding. Within a few years of its foundation the new agency achieved the successful co-ordination of diplomatic and service cryptanalysis under overall Foreign Office control, though for most of the interwar years diplomatic decrypts yielded much more valuable intelligence than service traffic. That co-ordination, equalled by no other major Sigint agency abroad, was one of the secrets of Bletchley Park’s success.
    For much of the 1930s the bitter rivalry between US naval and military Sigint agencies closely resembled that between their Britishcounterparts during the First World War. Each sought to crack independently the same diplomatic codes and ciphers in order, according to a declassified official history, to ‘gain credit for itself as the agency by which the information obtained was made available to the Government’. Though there was limited interservice collaboration at the end of the decade, the rivalry resumed after the breaking of the Japanese Purple diplomatic cipher by military cryptanalysts in September 1940, as