Correspondence and papers, 1842-[c. 1955], of poet and socialist Robert Jones Derfel and including letters and cards, [c. 1852]-1905, from various correspondents; poetry and sermons, 1842-1913; scrapbooks, 1855-1905, containing material relating to Welsh socialism, etc.; books and pamphlets; and research material, 1911-[c. 1955], compiled by T. J. Roberts in the course of his study of Robert Jones Derfel.