Strachey's main interest in the later part of this period, mathematical semantics and programming theory, was disseminated chiefly through discussions, lectures and talks, or shorter papers, but not by any comprehensive publication during his lifetime (see MS. Eng. misc. b. 293/F.61-MS. Eng. misc. b. 294/F.75).

Much of the work was collaborative with Strachey's colleagues in the Programming Research Group, notably D. Park, D. Scott and J.E. Stoy, and with research students such as R. Milne, C. Wadsworth; contributions from these and others are included in the folders and idenfied where possible.

Guidance from M. Harper and J.E. Stoy on the content and dating of some of this material is very gratefully acknowledged.