Important documentation of the post-War development of the Nuclear Physics Research Laboratory survives. There are Rotblat’s notes and correspondence relating to the synchro-cyclotron building project: these cover costs, equipment specifications and building design. Progress reports, architects’ plans and photographs are also included. A good record of his teaching is provided by a series of well-ordered manuscript notes for undergraduate lectures dating from 1939 to 1948. There are also some notes for ‘radio teaching’ and general correspondence and papers covering course planning, undergraduate examination results etc. A sizeable body of general correspondence survives from the second half of the 1940s; of exceptional interest is Rotblat’s correspondence with Chadwick (February 1945-1949) which encompasses a wide range of topics and issues, professional, personal and political. The principal topic is the running of the laboratory and the re-construction work; others include the Nuclear Physics Sub-Committee and national atomic research, the state of Poland, Rotblat’s family matters and his hopes for British citizenship. Further correspondence (1945-1950) is with the Ministry of Supply and the Atomic Energy Research Establishment and largely concerns equipment and staffing needs for photographic emulsion and cyclotron work.