Papers, 1889-1988, of Ben G. Jones, including academic notes, 1932-1935; personal letters, 1942-1968; political papers, 1935-1985; correspondence relating to politics in Merionethshire, 1963-1967; press cuttings, 1958-1963, printed material relating to the four main political parties in Wales, 1949-1966; papers relating to the Honourable Society of Cymmrodorion, 1939-1988; minute book, 1889-1909, of the London Welsh Mutual Improvement Societies' Union; papers deriving from the compilation and publication of the Dictionary of Welsh Biography, 1953-1986; papers relating to his public life, 1968-1984, including the Kilbrandon Commission, 1936-1969, the BBC, 1968-1978, UCW Aberystwyth, 1968-1985, and the Agricultural Land Tribunal, 1980-1984; minute book, 1889-1909, of the London Welsh Mutual Improvement Societies' Union; and papers relating to the status of the Welsh language and to teaching and broadcasting through the medium of Welsh, 1965-1987.

Family papers of the Williams family of Castell Deudraeth, 1859-1929, including a bound volume containing papers, including letters and press cuttings, relating to the general election of 1859 in Merionethshire in which David Williams stood as a Liberal against the sitting Conservative Member W. W. E. Wynne of Peniarth; scrapbooks, 1903-1929, containing press cuttings concerning the family, notably Sir Arthur Osmond Williams, and two typescript essays.

Papurau Hugh Roberts, 1877-1902, yn cynnwys penillion a cherddi, dwy ddrama fer ynglŷn â dirwest, nodiadau ac anerchiadau ar y dosbarth gweithiol a hawliau gweithwyr, anerchiadau a llythyrau at y wasg yn esbonio ei ddaliadau gwleidyddol ac yn ymwneud ag ymgyrchoedd etholiadol, nodiadau bywgraffyddol yn manylu ar ei gyfnod yn chwarel Bryneglwys a nodiadau a llythyrau ynghylch hanes Abergynolwyn = Papers of Hugh Roberts, 1877-1902, including verses and poems, two short plays concerning temperance, notes and addresses on the working classes and workers' rights, addresses and letters to the press expounding his political views and relating to election campaigns, autobiographical notes detailing his period at Bryneglwys quarry and notes and letters concerning the history of Abergynolwyn.