Gwrddlew was born about 480 AD at Twrcelyn commote, Anglesey, Wales.
His father had moved from southern Scotland with his family after being deposed in the turbulence caused by the Anglo-Saxon settlement of Britain.
This was formerly a chapelry within the parish of Llanddewi Brefi, Cardiganshire, but as of 1907 was a separate benefice.
[7] Nicholas Roscarrock lists 7 January as the festival of Gwrthelu, who may be identified with Gwrddelw.
In the account of the hunting of the boar Twrch Trwyth, in the Welsh romance of Culhwch and Olwen, there is a huntsman of Arthur's called Eli, who pursues Grugyn, one of the Twrch's offspring, to Garth Grugyn in Ceredigion.