Bede's Ecclesiastical History of England, ed. by A.M. Sellar, , at sacred-texts.com
AT that time, the West Saxons, formerly called Gewissae,in the reign of Cynegils,received the faith of Christ, through the preaching of Bishop Birinus,who came into Britain by the counsel of Pope Honorius ; having promised in his presence that he would sow the seed of the holy faith in the farthest inland regions of the English, where no other teacher hadbeen before him. Hereupon at the bidding of the Pope he received episcopal consecration from Asterius, bishop of Genoa, but on his arrival in Britain, he first came to the nation of the Gewissae, and finding all in that place confirmed pagans, he thought it better to preach the Word there, than to proceed further to seek for other hearers of his preaching.
Now, as he was spreading the Gospel in the aforesaid province, it happened that when the king himself, having received instruction as a catechumen, was being baptized together with his people, Oswald, the most holy and victorious king of the Northumbrians, being present, received him as he came forth from baptism, and by an honourable alliance most acceptable to God, first adopted as his son, thus born again and dedicated to God, the man whose daughterhe was about to receive in marriage. The two kings gave to the bishop the city called Dorcic,there to establish his episcopal see; where having built and consecrated churches, and by his pious labours called many to the Lord, he departed to the Lord, and was buried in the same city; but many years after, when Haedde was bishop," he was translated thence to the city of Venta,and laid in the church of the blessed Apostles, Peter and Paul.
When the king died, his son Coinwalch succeeded him on the throne, but refused to receive the faith and the mysteries of the heavenly kingdom; and not long after he lost also the dominion of his earthly kingdom; for he put away the sister of Penda, king of the Mercians, whom he had married, and took another wife; whereupon a war ensuing, he was by him deprived of his kingdom, and withdrew to Anna, king of the East Angles, where he lived three years in banishment, and learned and received the true faith; for the king, with whom he lived in his banishment, was a good man, and happy in a good and saintly offspring, as we shall show hereafter.
But when Coinwalch was restored to his kingdom, there came into that province out of Ireland, a certain bishop called Agilbert, a native of Gaul, but who had then lived a long time in Ireland, for the purpose of reading the Scriptures. He attached himself to the king, and voluntarily undertook the ministry of preaching. The king, observing his learning and industry, desired him to accept an episcopal see there and remain as the bishop of his people. Agilbert complied with the request. And presided over that nation as their bishop for many years. At length the king, who understood only the language of the Saxons, weary of his barbarous tongue, privately brought into the province another bishop, speaking his own language, by name Wini,who had also been ordained in Gaul; and dividing his province into two dioceses, appointed this last his episcopal see in the city of Venta, by the Saxons called Wintancaestir. (Winchester) Agilbert, being highly offended, that the king should do this without consulting him, returned into Gaul, and being made bishop of the city of Paris, died there, being old and full of days. Not many years after his departure out of Britain, Wini was also expelled from his bishopric by the same king, and took refuge with Wulfhere, king of the Mercians, of whom he purchased for money the see of the city of London,and remained bishop thereof till his death. Thus the province of the West Saxons continued no small time without a bishop.
During which time, the aforesaid king of that nation, sustaining repeatedly very great losses in his kingdom from his enemies, at length bethought himself, that as he had been before expelled from the throne for his unbelief, he had been restored when he acknowledged the faith of Christ; and he perceived that his kingdom, being deprived of a bishop, was justly deprived also of the Divine protection. He, therefore, sent messengers into Gaul to Agilbert, with humble apologies entreating him to return to the bishopric of his nation. But he excused himself, and protested that he could not go, because he was bound to the bishopric of his own city and diocese; notwithstanding, in order to give him some help in answer to his earnest request, he sent thither in his stead the priest Leutherius,his nephew, to be ordained as his bishop, if he thought fit, saying that he thought him worthy of a bishopric. The king and the people received him honourably, and asked Theodore, then Archbishop of Canterbury, to consecrate him as their bishop. He was accordingly consecrated in the same city, and many years diligently governed the whole bishopric of the West Saxons by synodical authority.