1950 letter is re paper by R.P. Bambah. Correspondence 1963-65 is on general research problems, appointments, publications, etc.
D.89: 'Old material for book': Contents of a folder so inscribed, consisting of extensive ms. notes and drafts kept in their original order. Continuous sequences have been clipped together for ease of reference. Some material probably dates from 1947. Professor B. J. Birch has contributed (February 1986) the following explanatory note: 'All of this can be regarded as material for his book on "Higher Arithmetic", though only a small proportion of these notes survived into the printed version. Probably the material was "tested" in lectures at UCL (and maybe Bangor).'
D.90: Correspondence. Correspondence with Hutchinson's University Library, publishers, and correspondence with reviewers, L. Schoenfeld and P. T. Bateman, 1953, with 1p. ms. note of where reviews appeared.
D.91-92: General correspondence with colleagues and others, arranged in alphabetical sequence.