  Alan Turing did not fit easily with any of the intellectual movements of his time, aesthetic, technocratic or marxist. In the 1950s, commentators struggled to find discreet words to categorise him: as ‘a scientific Shelley,’ as possessing great ‘moral integrity’. Until the 1970s, the reality of his life was unmentionable. He is still hard to place within twentieth-century thought. He exalted the science that according to existentialists had robbed life of meaning. The most original figure, the most insistent on personal freedom, he held originality and will to be susceptible to mechanisation. The mind of Alan Turing continues to be an enigma.