The collection is composed of the following:
Boxes 1-11:
- Drafts, copies of drafts, annotated drafts, and copy cut and copy edited material
Box 12:
- News cuttings on the deaths of the Koestlers
- Discarded folios
Box 13:
- Correspondence with Macmillan, publisher, 1981-1982
- Correspondence with publishers, 1979-1982
- Artwork for book
- Transcriptions
- Copies of letters: Cynthia's and Mamaine's, 1945-1955
- Academic correspondence
Box 14:
- Notes for talks; Montage
- Correspondence / Promotion, 1970s-1980s
- Correspondence, 1974-1982
- Reviews / Correspondence, 1970s-1980s
- Unsorted material
- Reviews, 1982 / Encountering Koestler / Correspondence
- Essay
Box 15:
- Reviews of Koestler's works / Cuttings, 1970s
- Reviews / Cuttings, 1950s
- Material on capital punishment
- Cuttings on various themes, 1960s-1980s
- Correspondence - Responses to Hamilton letter, 1970s
Box 16:
- Reviews, 1980s
- Correspondence, 1980s-1990s
- Copies of letters from E. M. Forster, Mann, Huxley and others, 1940s
- Copy for notes
- Outline / Synopses