The papers, though not exhaustive, provide some useful material on Bretscher's career and some of the momentous events in which he participated. There is biographical material including Bretscher's own 'Survey of activities during the war and with the A.E.R.E.', compiled in 1964 and a lecture given at Harwell in 1967 on 'Wartime nuclear physics and chemical research at the Cavendish Laboratory 1940-1944 associated with atomic weapons'. Very little remains of his early work in Switzerland and there is only a little material on the early stages of his atomic research at Cambridge and the collaboration with D.E. Lea. Much better documented is the work undertaken at the Cavendish Laboratory for the 'Tube Alloys' Project. There are research notes and reports by members of the team, reports prepared for the Maud Committee and the Department of Scientific and Industrial Research, Bretscher's regular exchanges of correspondence with J. Chadwick and records of later work relating to postwar publication of the wartime research.
Because of the exceptionally tight security virtually no personal research material remains from the Los Alamos period. There are, however, a number of final reports contributed to the sequence of 'L.A.' reports, some personal correspondence, circulars and newsletters, and press-cuttings. The largest body of material relates to Bretscher's postwar career at Harwell and documents his involvement in national and international nuclear data committees, and his interest in maintaining collaboration with universities and other research institutions. The surviving correspondence is scanty with few substantial exchanges.