Deeds and documents relating to Trimsaran Coal, Iron and Steel Company, [c. 1861]-1872; Ynisarwed Resolven Colliery Company, 1866-1875; and Yniscedwyn Iron, Steel, and Coal Company, 1837-1875; and copies of Court Rolls of the Manor of Evenjobb, Radnorshire, 1798-1851.

Deeds, 1609-1873, mostly relating to lands in Carmarthenshire, including the Trimsaran estate; records of the Commissioners of the Kidwelly and Llanelli Canal and Tramroad Act, 1813-1834; and deeds and records of the Llanelli Canal and Tramroad Company, 1834-1839. The fonds does not contain any records relating to the Carmarthenshire Antiquarian Society.

Personal papers of Sir John Williams comprising notes, essays, lectures and transcripts by him, [19th century]-[early 20th century]; certificates and testimonials, 1858-1915; cards and letters from the children of King George V and invitation cards to royal functions, 1889-1916; documents relating to his various honours, 1894-1911; photograph and stamp albums, 1849-[early 20th century]; other photographs, [1840s]-1905; press cuttings, [c. 1870]-1926; letters collected by Sir John, 1633-1912; letters to him, 1879-1922, the correspondents including members of the Royal Family; deeds and other documents relating to properties in Llangadog, to Plas Llanstephan and to Harley Street, London, 1790-1918; bibliographical material, [19th century]-[20th century]; medical notebooks and other papers, 1855-1900; diaries of Sir John and Lady Williams, 1872-1925; estate and financial records, 1890-[1926]; papers relating to public affairs, 1870-1911; miscellaneous items collected by Sir John, 1795-[c. 1919]; personal possessions, including University and commemorative medals, insignia, medical equipment, and ceremonial trumpets, 1861-1913; and deeds collected by Sir John Williams, 1546-1869, comprising deeds of the Vaughan family of Llanelli, Carmarthenshire, the Penry family of Swansea, Glamorgan, and the Dalton family of Pembrey, Carmarthenshire, 1545-1677, relating to properties in Llangennech and Pembrey, Carmarthenshire; deeds of John Jones, Ystrad, Carmarthenshire, relating to Llansadwrn, Carmarthenshire, 1632-1793, and the borough of Carmarthen, 1611-1869; Wynn of Gwydir deeds, 1352-1797, relating mostly to Caernarfonshire, Merionethshire and Denbighshire; miscellaneous Welsh deeds, relating mainly to properties in Carmarthenshire and Cardiganshire, 1451-[c. 1840]; and miscellaneous deeds relating to England (mainly Cornwall and Staffordshire), Ireland, and Scotland, 1586-1896.

The file includes material relating to agriculture, industry and the Royal Ordnance Factory at Pembrey.

Papurau'r Parch. Richard Ellis Williams, rhai eglwysig yn bennaf, 1802-1950, yn cynnwys cyfrolau o nodiadau pregethau, 1887-1918; pregethau, 1883-1926; gohebiaeth R. A. Ellis Williams yn ymwneud â Chymdeithas Hanes Bedyddwyr Cymru a Gwobr Goffa Richard Ellis Williams, 1947-1950; a phregethau Humphrey Ellis, Salem, Cwmfelin, [1860]-1870. = Papers of the Rev. Richard Ellis Williams, mainly ecclesiastical, 1802-1950, including volumes of sermon notes, 1887-1918; sermons, 1883-1926; correspondence of R. A. Ellis Williams relating to Cymdeithas Hanes Bedyddwyr Cymru and Y Gwobr Goffa Richard Ellis Williams, 1947-1950; and sermons of Humphrey Ellis, Salem, Cwmyfelin, [1860]-1870.

Papurau Berllanydd, [1929]-1984, yn cynnwys dyddiaduron, 1929-1933,1935-1970, 1982-1984, papurau personol yn cynnwys copïau o'i ewyllys,1981,nodiadau ar gyfer pregethau, anerchiadau crefyddol a gwaith bugeiliol, barddoniaeth a deunydd eisteddfodol, torion papur newydd a deunydd printiedig. = Papers of Berllanydd, [1929]-1984, comprising diaries, 1929-1933, 1935-1970, 1982-1984, personal papers including copies of his will, 1981, notes for sermons, religious addresses and pastoral work, poetry and eisteddfod material, newspaper cuttings and printed material.