• Welchman was a Cambridge don who agreed along with a number of other ‘men of the professor type’, to report to Bletchley Park in the event of war.

  • Welchman arrived at Bletchley Park on September 4, 1939 and remained working there until the end of the war.

  • Within a few months of his arrival, Welchman, on his own initiative had reinvented a key part of the pre-war work of the Polish codebreakers. Through his work on traffic analysis, he had laid the foundations for SIXTA, a fusion of signal intelligence and cryptography.

  • He was one of the first to recognise the need for a rapid expansion of BP’s infrastructure for the decryption and analysis of intercepted Enigma traffic. He drew up an organisational plan which would enable BP to achieve such an expansion. Welchman’s plan became Bletchley Park’s working model for the rest of the war.

  • Along with Alan Turing, he developed a radically new production-orientated approach to machine cryptanalysis. His invention of a device called the Diagonal Board, turned Turing’s design for the ‘Bombe’ into a workable machine.

  • He took on the leadership of the group in Hut 6 which would ultimately decrypt close to one million German Air Force and Army signals. 

  • After moving to the United States in 1948, he was involved in Project Whirlwind, an M.I.T. project which would apply for the first time, computers to air traffic control and air security.

  • He gave the first course of lectures on programming for a digital computer at M.I.T.

  • Welchman’s work at Bletchley Park contributed to the birth of the digital age and his post-war career helped nurture it through its infancy.

  • In 1982, Welchman published The Hut Six Story, the first account of how Bletchley Park actually decrypted German communications on an industrial scale throughout the war.

  • After the publication of his book, Welchman was harassed and ostracised by GCHQ and the NSA until his death in 1985.

Image: Gordon Welchman visiting his daughter, Rosamond, in Paris 1972.