[4] Land grants in the Book of Llandaff show Oudoceus as a contemporary of late 7th-century kings of South Wales.

[5] His associations with Llandaff are very strong and it seems he was an early patron of the church there, where he is said to have placed relics of Saint Teilo, one of his predecessors as bishop.

Oudoceus's 12th-century hagiographic 'life' in the Book of Llandaff tells how he was the son of King Budic of Brittany,[8] born in that country shortly after his father's return there from exile in Dyfed.

His mother, Anawed, was said to be the sister of Saint Teilo[1] and Budic promised that Oudoceus could train for a life in the Church under him.

[9] There is no evidence that Llandaff was the centre of a bishopric until at least the early 11th century, and it is now thought that Oudoceus could have been based at Llandeilo Fawr or at Llandogo, where he is said to have been a bishop in c.580.