Bishop of Dorchester-on-Thames 650–60; bishop of Paris 668–c.690. Frankish by birth, Agilbert studied in Ireland for several years under teachers of Roman sympathy and was probably consecrated bishop there. He came to Wessex in 650, where King Cenwalh (643–74) gave him the see of Dorchester, recently founded by Birinus. Although famous for learning and industry, Agilbert did not speak the Wessex dialect. This was the ostensible reason for Cenwalh dividing his kingdom into two dioceses and establishing Wine as bishop of Winchester without consulting Agilbert. In reality, the division corresponded to the distribution of two tribes which came to Wessex from East Anglia and along the Thames on the one hand, and from the Continent via Southampton on the other. Agilbert took offence and departed: he was next heard of taking part in the Synod of Whitby (663/4) as the senior prelate on the ‘Roman’ side, but he invited Wilfrid, whom he had recently ordained priest, to be the principal spokesman in his place, as his own knowledge of Old English was imperfect.
After the Synod he returned to Gaul, consecrated Wilfrid (with other bishops) at Compiègne, and became bishop of Paris. He became closely associated with Ebroin, the notorious Mayor of the Palace. But in 668–9 Theodore spent a long time on his way to England as Agilbert's guest, learning from him much about the state of the Church in England.
Agilbert died and was buried at the monastery of Jouarre, where his sister was abbess. His fine 7th-century sarcophagus survives there. There is no liturgical evidence for an early cult. Agilbert was never formally canonized, even after an investigation of his relics in the 18th century. But some implicit approval of his cult was given, as is shown by the presence of his feast on 1 April in a calendar compiled under King James II for English Catholics in 1686.
From The Oxford Dictionary of Saints in Oxford Reference.