Records of the Brogyntyn estate, home of the Ormsby-Gore family, Barons Harlech, 1296-1951. They include estate papers and deeds, legal papers, financial papers, family papers and county administration papers of the Ormsby-Gore family, their ancestors, the Maurices and the Owens of Clenennau, the Wynns of Glyn and others, such as Anwyl of Park, Clayton of Lea Hall, Godolphin of Abertanat, Lyster of Penrhos, Mostyn of Nant, and Vaughan of Corsygedol. The three main estates represented in the collection are Brogyntyn, Clenennau and Glyn, the latter constituting a major addition to the existing North Wales holdings of Sir Robert Owen upon his marriage to Margaret Wynn in 1683. The documentation also covers other, subsiduary estates acquired by marriage or inheritance, namely Llanddyn, Sylfaen, Ystumcegid, Nant, Cemais, Penrhos, Abertanat and properties in the west of Ireland. The record types include title deeds for lands in Caernarfonshire, Merionethshire, Flintshire, Denbighshire, Montgomeryshire, Shropshire, elsewhere in England and Wales, and in the Irish counties of Westmeath, Leitrim, Sligo, Mayo and Roscommon, 1296-1838; rentals, accounts and other papers associated with estate administration, [1380s]-1951; manorial records, 1429-1804; household management papers, 1662-[c. 1949]; legal and arbitration papers, 1410-1834; financial papers such as mortgages and accounts, 1492-1876; family settlements, probate records and trusts, 1485-[c. 1862]; private letters, 1582-1950; papers relating to family interests, [14th cent.]-1951; personal papers of family members, 1672-1945; royal appointments and honours, 1795-1948; central government papers, 1581-1887; county administration papers, 1518-1904; and administration records of the church, schools and charities, 1598-[1876x1904]. Other component parts of the archive are the Clenennau Letters and Papers, which combine personal correspondence with the civil and military administration of Caernarfonshire from the late sixteenth to late seventeenth centuries. Additional records, comprising Lord Harlech's Game Books (3 volumes), 1882-1933, a journal kept by W. R. Ormsby Gore of the 13th Light Dragoons, May-September 1854, two manuscript catalogues of plays, 1815, and a manuscript catalogue of the library at Porkington, 1809, were acquired in March 2017.
The Brogyntyn (Longueville) group comprises deeds and documents relating to the Brogyntyn estate, 1607-1977, deposited by Longueville Gittins solicitors who provided professional legal services to the estate.

Official documents and other papers, 1675-1727, many of them addressed to the deputy lieutenants, etc. of Caernarvonshire and relating to the militia, musters, the confiscating of weapons in the possession of Papists, etc. Among the correspondents are Henry, 3rd marquis of Worcester and first duke of Beaufort, Lord President of the Council in the Marches of Wales, Col. Thomas Mostyn of Gloddaeth, John Wynne of Whitehall, mustermaster for Caernarvonshire, and Richard, 3rd baron Bulkeley of Baron Hill. The documents include a statement by Thomas Glynne relating to a 'conventicle' at the house of Ellis Owen, Llangybi, at which James Owen preached; a memoranandum by Thomas Mostyn relating to the refusal of William Wynne, sheriff of Flintshire, to read the proclamation of King George II at Holywell; and some papers of general North Wales interest.

Commonplace books containing miscellaneous extracts mainly from printed sources, and relating to North Wales.

Treatises in Latin; a Greek vocabulary; material relating to the hundreds and parishes of Merioneth, Montgomeryshire and Pembrokeshire; 'the Syren & the hundredes of Engelonde'; rentals of several North Wales manors; an account of a tax paid by North Wales counties in 1701; a transcript of documents of King Alfred; etc.

A volume compiled by J. H. Davies labelled 'North Wales' and containing press cuttings, notices, copies of photographs and engravings, etc. relating to North Wales and North Wales families.

References and extracts, relating mainly to North Wales affairs, taken from issues of The Rhyl Journal for 1905-1911.

Minute books, correspondence and papers, 1953-1992, relating to the Conservative Party in North Wales, including general political papers and circulars, 1971-1989; papers of the North Wales European Election, 1989; news sheets produced by the Brecon and Radnor Conservative Association, 1963-1972; papers relating to the training of constituency agents, 1970-1978; minutes and correspondence of the executive council of the Caernarvon Division of the Conservative and Unionist Association, 1953-1992; papers concerning the Pwllheli Conservative Club, the Association's Annual General Meetings, briefings and reports, 1982-1992; papers including minutes of the executive council and other committees; correspondence, circulars, memoranda, balance sheets of the Conway Constituency Conservative and Unionist Association, 1967-1982; minutes of the Llandudno Junction branch, 1951-1986; records of the Denbigh Constituency Conservative Association, 1974-1982; papers of the National Society of Conservative and Unionist Agents, both the National and Wales and Monmouthshire branches, 1970-1980; and minutes of the North Wales European Constituency Conservative Council, 1978-1989.

Press cuttings, some of them of North Wales interest.

North Wales pedigrees copied from 'Llyfr Melyn Tyfrydog', which is said to be a transcript, made [c. 1766], by Hugh Hughes ('Y Bardd Coch') of a manuscript owned by Lewis Morris; papers relating to persons and places in North Wales and to the diocese of Bangor; 'englynion'; correspondence between W[illiam] Wynn Williams, Jonathan Jones and Lady Chandos Reade; etc.

Pedigrees, genealogical notes, letters, pamphlets, etc. relating to North Wales collected by Hugh Robert Hughes (1827-1911).

Correspondence and papers of Beata Brookes: papers relating to the 1979 Euro-election campaign in North Wales, 1979; correspondence with local Conservative Associations, 1978-1984; North Wales European Constituency Conservative Council papers, 1976-1984; correspondence on European issues, 1979-1988; correspondence with local authorities, 1980-1989; papers relating to charities for the mentally handicapped, 1985-1989; constituency correspondence, 1985-1989; Conservative Party correspondence, 1985-1989; general correspondence, 1979-1987; printed material, 1984-1988; correspondence with Margaret Thatcher, 1984-1987; and correspondence from John Major, 1993.

A collection of transcripts, mainly by Robert Vaughan, Hengwrt, of records relating to North Wales, including the extent of North Wales by John de Delves, 26 Edward III; a record of a view of frankpledge for the commote of Menai, 28 Henry VIII; ministers' accounts for Flintshire, 30-31 Henry VIII; extracts from miscellaneous inquisitions, rentals, court rolls, and correspondence; receipts of Lewis Owen, deputy receiver of North Wales, 1 & 2 Philip and Mary; notes of leases under the exchequer seal, 1579; notes on the form of administration of justice in Wales by Auditor Hill; 'The State of the Dominion of Wales' by Sir Thomas Canon; accounts of John Lloyd of Ragad, escheator of Merioneth; instructions to the Earl of Bridgewater, President of the Council in Wales and the Marches, 1633; a roll of the coroner for Merioneth, 10-11 Edward III; estreats of fines in North Wales, 22-30 Edward III; lists of persons indicted in Merioneth, 6- 19 Richard II; records of pleas before the justice of North Wales, 4 Edward II; a list of recognisances in the exchequer at Caernarvon, 18 Edward II; lists of persons in Anglesey fined for being in arms with Owen Glyndyfrdwy, with lists of outlaws and jurors; and a breviate of an account between Sir John Salesbury, chamberlain of North Wales, and Lewis Owen, his deputy, 1555.

Transcripts of records relating to North Wales, being the text of the Additamenta printed in The Record of Caernarvon, 1837, pp. 296-303, from Harleian MS 4776.

Rentals of crown and other lands and manors in various parts of North Wales, including rents due to John Edwards, Chirk, together with three documents relating to land in the lordship of Chirk and Flintshire.