A file of correspondence and papers accumulated by Alan Turing in relation to his work in the University's Computing Machine Laboratory. The material dates from March 1949 until just before Turing's death in June 1954. It is assumed to comprise an important segment of his 'official' correspondence during this period, although it is unlikely to constitute the entirety of his CML correspondence.

The letters sent to Turing include comments on his published articles, and in some cases, unpublished research, as well as requests to lecture, attend conferences, supply drafts or offprints of his articles, and generally give advice. A number of letters are requests to view or use the Mark I/Ferranti Mark I computers, which were Turing's administrative responsibility as deputy director of the CML.

In a few cases, there is extended correspondence between Turing and some individuals about particular issues; for example, William Boone, an American academic, who was reviewing Turing's article "The word problem in semigroups with cancellation" and Beatrice Worsley (1921-1972), a Canadian student, who had studied with Turing in the UK and later continued her research at the University of Toronto. Some of Turing's more well-known peers and associates are also represented including: SP Frankel, Maurice Wilkes, Christopher Strachey, Robin Gandy, Vivian Bowden, JBS Haldane, Gilbert Ryle, Alonzo Church, Oskar Morgenstern, Sir Eric Jones, and HSM Coxeter. There is very little in the way of personal correspondence, and no letters from Turing family members. The correspondence includes discussion primarily of Turing's research on chemical morphogenesis in plants, but also his articles on "The word problem in semigroups with cancellation', "Some calculations of the Riemann Zeta-function", "Computing machinery and intelligence" and two "popular" essays on "Digital computers applied to games" [although parts of this essay were written by others], and "Solvable and unsolvable problems".

Turing's copy letters in this file are almost entirely type-written, and mainly addressed from the Computing Machine Laboratory. They are not usually initialled, and it is assumed most were dictated by Turing to his secretary Miss S J Wagstaff. In a few cases, Turing has annotated letters with marginal comments etc.