Papers of Gwyn Thomas, comprising autobiographical material, [c. 1946]-[c. 1972]; drafts, typescripts, notebooks and photocopies of novels and stories, [c. 1935]-1974; plays, including reviews of plays, [1940s]-1978; essays, articles and lectures by or about GT, 1926-1985; scripts for radio and television, including tributes to GT 1948-1988; book reviews, 1961-1971; professional and personal correspondence of GT and occasionally other family members, 1931-1985; letters to and from his wife, Lyn Thomas, after his death, 1981-1984; cuttings, 1937-1986; photographs; miscellaneous personal and literary papers [post-1913]-1984; notebooks [c. 1935]-[1970s]; and material collected by GT's biographer, Michael Parnell, including drafts and notes for the biography, notes , articles and correspondence on GT and his works, [c. 1984]-1989. Further manuscripts comprise a notebook, typescripts of two plays and letters.

Papers relating to and created by Margiad Evans (Peggy Eileen Whistler), [1930s]-[1958x1965], comprising material for an unpublished critical biography of Margiad Evans, compiled by W. Arnold Thorpe, [1936x1965], including transcripts by Thorpe of poems, prose and letters by Margiad Evans, scripts of radio broadcasts and extracts of reviews of Margiad Evans's published prose works; correspondence relating to information on Margiad Evans; biographical and related material; Whistler family photographs; notes by W. Arnold Thorpe and source material; together with manuscripts and papers of Margiad Evans, including drafts and copies of poems, some unpublished [c. 1945]-[1958]; unpublished and published prose works, [c. 1930s]-[1958]; notebooks and journals, which include drafts of poems and prose pieces, 1942-[1950s]; correspondence, mainly from Margiad Evans to her husband, 1934-1958; reviews of Autobiography and A Ray of Darkness[1943-1952]; drawings including drawings representing eighteen out of the thirty illustrations for Alfred Williams, Tales from the Panchatantra (Oxford, 1930); and family papers, 1939-[1950s].

Additional papers donated October 2021: see added Series.