From Dictionary of Literary Biography, Volume 201: Twentieth-Century British Book Collectors and Bibliographers:
In his introduction to his bookseller friend David Low’s autobiography, With All Faults (1973), Greene remarked that if he had not been a writer he would have liked to have been a secondhand bookseller….
The main source of information about Greene’s book-collecting activities is The Annotated Library of Graham Greene (1993), an extensively annotated catalogue of the books and letters owned by Greene and passed [on] just before Greene’s death in 1991. Approximately five hundred of the three thousand books in the collection were presentation copies from fellow authors such as Ford Madox Ford, Malcolm Muggeridge, Evelyn Waugh, and Vladimir Nabokov. Inserted loosely in the books were more than 150 letters from figures including poet W. H. Auden and Guy Burgess, the British traitor who spied for the Soviet Union….
Books and their acquisition were closely bound up with Greene’s creativity. While waiting in airports and restaurants or reading at home, he wrote in the margins of his books ideas and images that sometimes became creatively transformed into short stories or novels–Dennys and McNeil estimate that in the books that comprised his collection at the time of his death there were “25,000 to 30,000 marginal linings.”