Consists primarily of the working drafts, sometimes many versions, of the manuscripts for eighteen novels and three short stories, as well as fragments of two playscripts, the typescript of the television adaptation of his first novel The Strumpet Wind (1947), and drafts of three essays. The drafts are undated but range from early versions of The Lord Won't Mind to the unpublished draft of The Good Life, a novel which Merrick was working on when he died. Not all of the novel manuscripts in the collection were published, and not all of the published novels are represented by manuscripts in the collection. Merrick did not date any of his manuscripts.

There is also correspondence in the collection, including three boxes of business and financial correspondence, dating from 1967 until Merrick's death in 1988, then a folder of correspondence dated 1989-1990, dealing with the Merrick estate, as well as one folder of undated material. There is very little personal correspondence but what has been preserved includes nine letters and notes from E.M. Forster, dating from 1948 to 1954. There is also fan mail, dating from 1977 until the year after Merrick's death. The documents in the collection include photographs, awards, passports, and some medical and financial records. There are publicity photographs, as well as photographs from Merrick's personal collection, dating from 1959 to 1987. The diaries and calendars in the collection date from 1967 to 1988. The printed material in the collection is primarily clippings, but includes some of Merrick's published journalism as well as playbills from his stage career. The series "Papers of Other Persons" consists of a small amount of material relating to Merrick's life-long partner Charles Hulse.