monk and bishop. Reputedly a descendant of Coel Godebog, a Celtic chieftain of North Britain, Deiniol founded the two monasteries of Bangor Fawr (on the Menai Straits) and Bangor Iscoed (Clwyd), which became, according to Bede, the most famous monastery of British Christianity and came to number over 2,000 monks before they were routed at the battle of Chester by the pagan Æthelfrith, king of Northumbria. Later Deiniol was regarded as ‘first bishop of Bangor’ (Gwynedd) and his reputed area of influence was consolidated in the Norman (and modern) diocese. There are, however, in the Flintshire (Clwyd) area Deiniol dedications at Marchwiail and Worthenbury which perhaps inspired the dedication of W. E. Gladstone's famous library at Hawarden; also (according to Baring-Gould) at Llanuwchllyn and Llanfor, near Bala. There are a few dedications in S. Wales and one in Gwent at Itton (formerly called Llandeiniol). In the Life of David by Rhygyvarch, Deiniol and Dyfrig were the two bishops who finally persuaded David to take part with them at the famous Synod of Brefi (c.545). Whether this was concerned with Pelagianism or (more likely) with penitential discipline, it is significant that Deiniol was considered comparable to the other two Welsh bishops. Feast: 11 September.
E. G. Bowen, The Settlements of the Celtic Saints in Wales (1956);Baring-Gould and Fisher, ii. 325–31;T. F. Tout in D.N.B., s.v. ‘Daniel’.