The papers are extensive, relating to almost every aspect of Blackett's career in science and public life. There is biographical and personal material including large numbers of letters of congratulation received on the occasion of the various scientific and public awards and honours with which Blackett's achievements were recognised. There are records of his work on particle disintegration, cosmic rays, astrophysics and magnetism in the form of laboratory notebooks, working papers, correspondence, lectures, publications and broadcasts. There is documentation of his activities on various defence projects and as a member of government committees before, during and after the Second World War. Blackett's political interests are represented by material relating to the Association of Scientific Workers, Labour Party discussion groups on science and technology policy and the Ministry of Technology instituted after the Party's 1964 electoral victory. There are records of a wide range of science-related interests such as the history of science and technology, science, education and government, and nuclear weapons and disarmament, and of his overseas activities including material relating specifically to India and that concerned with matters more generally affecting developing countries.

A few lacunae in the surviving material have been identified. There are no documents relative to Blackett's service with the National Research and Development Corporation or the Department of Scientific and Industrial Research and, of his correspondence during the Second World War, only that for 1942 survives.

Papers relating to the Committee on Scientific Research on Human Institutions of the Division of the Social and International Relations of Science of the British Association for the Advancement of Science, including minutes of meetings, papers written by members and the Committee's report.

Papers, 1930-1962, concerning lectures and publications by Hart, notably correspondence, 1951-1961, mainly relating to lectures on Leonardo da Vinci, aeronautical engineering and other subjects; correspondence relating to the writing and publication of his work, including James Watt and the history of steam power (Henry Schuman, New York, [1949]), 1948, and The world of Leonard da Vinci, man of science, engineer and dreamer of flight (Macdonald, London, 1961), 1960-1962; typescripts of lectures on textile education, 1951, the scientific basis for Leonardo da Vinci's work in technology, 1952, and handicraft instruction; typescript of The world of Leonard da Vinci, man of science, engineer and dreamer of flight (Macdonald, London, 1961), 1960; copies of published articles by Hart on medieval and modern science, 1930-1955.

Papers, 1893-1933, of John Henry Holmes, comprising diaries, 1893-1900, 1906-1907, 1915, including observations on his activities and on life in Papua and notes on subjects including anthropology; correspondence with Alfred Cort Haddon, 1904-1906, 1922, comprising letters received and copy letters sent and chiefly concerning Holmes' study of Elema totemism; typescript articles on Papuan beliefs, including the totemism of the Elema tribes, 1914 and undated; printed comparative tables of languages spoken in different parts of Papua, 1915; photographs showing examples of the technology of the Orokaiva tribes of northern Papua; sketch maps of Papua; manuscript notes on anthropology, 1913; typescript children's stories about missionary work and life in Papua, set in the Moru and Urika districts, 1933 and undated.

Agendas and minutes of the Board and its committees, 1893-1904, including the Scholarship Committee, Secondary Schools Committee, Polytechnics Committee, Teaching of Art and Technology Committee, Building Trades Committee, Commercial Education Committee, Domestic Economy Committee, Finance and General Purposes Committee, Higher Education Committee, Teaching of Chemistry Committee and Technical Instruction for Women Committee.

Also annual reports; issues of the London Technical Education Gazette, the official circular of the Board; pocket books; standing orders; special reports, including some prepared for the London County Council; proposals for new subjects of instruction; papers regarding scholarships and awards; inspection reports; maps of London showing centres of teaching art and science and technology; maps of London showing secondary schools for boys and girls; papers regarding individual polytechnics or schools including annual reports of the Bolt Court Technical School (later the School of Photo Engraving and Lithography); statistics; papers regarding the University of London and financial accounts.