Records deriving from administration of the Clenennau, Glyn, Sylfaen and Ystumcegid estates in Caernarfonshire and Merionethshire, 1530-1902. The lands belonging to Clenennau were situated in Penmorfa, Gest, Llanfihangel-y-pennant, Beddgelert, Llanystumdwy, Caernarfon town, Pwllheli, Treflys and Ynyscynhaearn, Caernarfonshire, and in Llanfair[-juxta-Harlech], Llanenddwyn, Llanfihangel-y-traethau, Penrhyn, Ffestiniog, Penllyn, Llanfrothen and Nanmor, Merionethshire. The Glyn and Sylfaen estates lay in Talsarnau, Llanfihangel-y-traethau, Llandanwg, Llandecwyn and Llanaber; and Ystumcegid in Llanfihangel[-y-pennant], Llanystumdwy, Penmorfa, Cricieth, Clynnog and Penyfed. The records from each estate are similar, comprising rentals and related papers, -1849, accounts, 1534-1827, leases, 1530-1842, correspondence, 1609-1888, and miscellaneous estate administration papers, 1662-1902. It is interesting to note the relationships of the Owen family with the eighteenth century estate stewards, notably Anne Jones of Clenennau, Griffth Parry, John Parry of Brynbanon and Humphrey Owen of Lasynys.