The catalogued portion of the archive contains records of the family of Owen, later Humphreys-Owen, of Glansevern, and Johnes of Garthmyl, mainly comprising title deeds and documents, [late 12 cent.]-1929, mainly relating to property in Montgomeryshire; estate papers, 1767-1924, including rentals, accounts and surveys; records relating to Campobello island, New Brunswick, Canada, 1767-1902; substantial family correspondence, 1633-1926, political correspondence of Arthur Charles Humphreys-Owen, 1856-1905, including letters from Lord Rendel; naval papers of Captain William Owen, 1746-1778, [c. 1797]. The uncatalogued part of the archive includes correspondence of the Owen and Humphreys-Owen families, 1754-1905; pedigree of the Owen family, 1839; and material relating to S. P. F. Humphreys Owen, [c. mid 20 cent].