Aldfrith (d. 705), king of Northumbria, son of Oswiu of Northumbria and an Irish princess of the Cenél nÉogain, was brought up in Ireland, where he spent many years in study. When his half-brother Ecgfrith died suddenly (685), he was brought to the throne of Northumbria with the assistance of his half-sister Ælfflaed, abbess of Whitby. The Fragmentary Annals of Ireland state that he was a pupil of Adomnán (qv), and all sources concur in calling him a learned man, including Bede, who described him as ‘a man very learned in the Scriptures’ (‘Historia ecclesiastica’, iv, 26). Aldhelm of Malmesbury, the first English man of letters, dedicated his ‘Epistola ad Acircium’ to one ‘who governs the realm of the northern empire’, which can only have been Aldfrith. He referred to a close spiritual relationship between them, going back many years, and also sent him a copy of his ‘Aenigmata’ (riddles). Almost certainly, then, Aldfrith was a pupil of Aldhelm, who had himself been taught by the Irish.
After Ecgfrith's marauding expedition to Ireland (684), Adomnán visited Aldfrith (686) to obtain the ransom of some eighty Irish prisoners taken in that raid in return for a text of his recent treatise on the Holy Places (‘De locis sanctis’); Aldfrith had copies made and distributed. Aldfrith also gave eight hides of land to the monastery of Jarrow in return for a copy of the ‘Cosmographia’, a compendium of classical geography. No Latin or Anglo-Saxon compositions are attributed to him, but there exists a large collection of Old Irish maxims and two poems ascribed to him under his Irish name, Flann Fína.
The basis of these ascriptions has not been adequately examined, but there is little doubt that Aldfrith was a man of considerable learning, with a competency in three languages, a remarkable achievement for a barbarian king. Under his reign, Northumbrian culture reached its greatest flowering in manuscript illumination, sculpture, and literature, fostered, no doubt, by his love of learning and art. He enjoyed a reputation for learning among both the Irish and the Anglo-Saxons: his death (705) is noted in several of the Irish annals, which concur in naming him ‘wise’ or ‘learned’; and Alcuin of York (c.732–804) gave him great praise as ‘king and teacher’. Aldfrith married Cuthburh, daughter of Ine of Wessex, by whom he had a son, Osred, who did not, however, carry on his father's achievements.