Ieuan ab Rhydderch ab Ieuan Llwyd
He was a native of Glyn Aeron, Cardiganshire. His father resided at Park Rhydderch; is described as lord of Genau'r Glyn and Tregaron in the same county, and was an ancestor to the Pryse family of Gogerddan, and in the female line to the Wynnes of Peniarth.
Ieuan ab Rhydderch appears to have been a collector of Welsh manuscripts, for a valuable volume of Welsh medieval romances, known after him as the White Book of Rhydderch, once belonged to him, and was later preserved in the Hengwrt Library. Another volume in the same collection, containing poems by Dafydd ap Gwilym, and supposed to be in that poet's own handwriting, has also probably come from Rhydderch's collection. Ieuan's own poetry is chiefly of a religious character, like his poems to the Virgin Mary and to St. David, which are published in the Iolo MSS. Three extracts from his works, as specimens of curious metres, are also printed in 'Cyfrinach y Beirdd'. Many other of his poems are preserved in the British Museum. Some are also found in Hengwrt MSS; Ieuan was also the writer of a poem in English.
- Dwnn's Heraldic Visitations, i. 15, 44
- Add. MSS. 14866, 14966, 14969, 14970, 14979, 15000