Letters to Sir William Maurice, 1609, [Sir John Owen], 1634, and Mrs [Jonet?] Owen, [c. 1637], William Wynn of Glyn, 1644, Sir Robert and Dame Margaret Owen, [1682x1698], 1698-1725, Ellen Owen, 1688-[c. 1702], Jane Owen, 1700-1703, William Owen, 1714-1765, Mary Owen, 1736-1779, Robert Godolphin and Ellen Owen, 1769-1793, Owen Ormsby, 1793-1796, Mary Jane Ormsby-Gore, 1810-1860, William Ormsby-Gore, 1822-1859, and William Richard Ormsby-Gore, 1880-1888, received from the Caernarfonshire and Merionethshire estate stewards, tenants, solicitors and other individuals concerning estate business, accompanied by occasional replies and relevant letters from third parties. Recurrent subjects include problems associated with tenancies and property repairs on the Clenennau, Glyn and Ystumcegid estates, accounts and outgoings, provision of commodities, family and local news, rights to sitting places in church, creation of burgesses, particularly at Cricieth, [1688x1702], 1793, 1796, enclosures, trespasses, crown lands, exploitation of timber and extraction of minerals (1880s especially). Particular topics of interest include the mortgage on Ystumcegid, 1688-1703; horse racing in Caernarfonshire, 1732; purchase of Dolbenmaen, 1735-1736; the construction of the Porthmadog railway; road improvement and other public works; the authority of the mayor and bailiff of Bala; building leases on Corporation land at Cricieth; and construction of a factory at Singrig [Llanfihangel-y-Traethau], 1841-1860. Several of the letters incorporate agent's accounts.

Mining leases and agreements for the extraction of lead and copper in Llanfrothen, particularly at Bwlch y Plwm, 1726, 1810, 1837, various minerals in Llanfihangel-y-pennant, Beddgelert, Penmorfa, Llanystumdwy and Ynyscynhaearn, 1757, 1823, and stone from a quarry in Penmorfa, 1840; and a detailed, illustrated report on the mineral mines and slate quarries belonging to William Ormsby-Gore in Caernarfonshire and Merionethshire, 1853.