In May 1948, Newman offered Turing the post as Deputy Director of the computing laboratory at Manchester University. Turing accepted, resigned from the NPL, and moved in October 1948. The meaningless title reflected Turing's uncertain status. He had no control over the project whose fate was in fact determined by its sudden necessity for the British atomic bomb project.
F. C. Williams had in any case built his own empire, and Newman's original plans were largely swept aside. But Turing did have a clear role to play: as the organiser of programming for the engineers' electronics.
Turing at Manchester could perhaps have led the world in software development. His partly explored ideas included the use of mathematical logic for program checking, implementing Church's logical calculus on the machine, and other ideas which, combined with his massive knowledge of combinatorial and statistical methods, could have set the agenda in computer science for years ahead. This, however, he failed to do; his work on machine-code programming at Manchester, produced only as a working manual, was limited in scope.
Instead, there followed a confused period, in which Turing hovered between new topics and old. He revisited his 1939 calculation of the Riemann zeta-function with the use of the prototype computer; he pursued the question of computability within the algebra of group theory. Out of this confused era arose, however, the most lucid and far-reaching expression of Turing's philosophy of machine and Mind, the paper Computing Machinery and Intelligence which appeared in the philosophical journal Mind in 1950.
This, besides summarising the view he had developed since 1936, absorbed his first-hand experience and experiment with machinery. The wit and drama of the Turing Test has proved a lasting stimulus to later thinkers, and the paper a classic contribution to the philosophy and practice of Artificial Intelligence research. But this was essentially the end of his investigation, and despite this model of communication, supported by his radio talks, he had apparently no influence on the American foundation of Artificial Intelligence later in the 1950s.
At the same time, in 1950, there emerged a clear direction for new thought. Rather than return to classical mathematics, the novel potential of the computer still held his attention, and he became a pioneer of its personal use. For, as he settled in Manchester, buying his own first house at outlying Wilmslow, he had an entirely fresh field in view. It was what he described as the mathematical theory of morphogenesis: the theory of growth and form in biology.
Outwardly an extraordinary change of direction, for him it was a return to a fundamental problem; even in childhood he had been spotted and sketched 'watching the daisies grow'; from childhood Natural Wonders to D'Arcy Thompson's On Growth and Form to a more recent interest in how brains grow new connections, he had sustained an interest in the biological structures so easily taken for granted, yet so complex and bizarre from the viewpoint of physics. Out of all the phenomena of life he fixed on the way asymmetry can arise out of initially symmetric conditions as first thing requiring explanation, and his answer, given without apparent reference to anyone else's work, was that it could arise from the nonlinearity of the chemical equations of reaction and diffusion. He modelled hypothetical chemical reactions on the circle and the plane, and for the repetitive numerical simulation required to test his ideas, became the first serious user of an electronic computer for mathematical research.
He was elected to Fellowship of the Royal Society in July 1951, for the work done fifteen years before, but equal originality was on the way: his first successful work on The Chemical Basis of Morphogenesis was submitted as a paper that November. Long overlooked, it was a founding paper of modern non-linear dynamical theory.