"Where Warnway [Vwrnwy] rolls its waters underneath
Ancient Mathraval's venerable walls,
Cyveilioc's princely and paternal seat."
Southey's Madoc.
Cynfyn, father of Bleddyn, King of Powys, by his consort Angharad, Queen of Powys, derived from Mervyn, King of Powys, third son of Rhodri Mawr (the Great), King of all Wales, progenitor of the three Dynasties of North Wales, South Wales, and Powys:
"... chi fu di noi
E de' nostri avi illustri il ceppo vechio."
"His [Owen Glyndwr's] father's name was Gryffyd Vychan: his mother's, Elena, of royal blood, and from whom he afterwards claimed the throne of Wales. She was eldest daughter of Thomas ap Llewelyn ap Owen, by his wife Elinor Goch, or Elinor the Red, daughter and heiress to Catherine, one of the daughters of Llewelyn, last Prince of Wales, and wife to Philip ap Ivor of Iscoed."—A Tour in Wales [by Pennant]: Lond. 4to. 1778, p. 302.
Of this celebrated antiquary, the author of British Antiquities Revived, and other valuable antiquarian works, the friend of Archbishop Ussher, Selden, Sir Simon d'Ewes, Sir John Vaughan, &c., it is observed in the Cambrian Register, "In genealogy he was so skilled, and his knowledge on that subject derived from such genuine sources, that Hengwrt became the Heralds' College of the Principality, and no pedigree was current until it had obtained his sanction."
His MSS. and library, formerly at Hengwrt, have been transferred to Rûg in Edeirnion, the present seat of his descendant, Sir Robert Vaughan of Nannau; and it may be confidently stated, that in variety, extent, rarity, and value, they surpass any existing collection, public or private, of documents relating to the Principality. Many of them are unique, and indispensable for the elucidation of Cambrian literature and antiquities; and their possessor, by entrusting, to some gentleman competent to the task, the privilege of preparing a catalogue raisonnée of them, would confer a public benefit which could not be too highly appreciated.