The Celtic monastic system was apparently in vogue among the remnant of the ancient British Church in Wales and the West Country on the coming of St. Augustine. Little is known with certainty, but as the British Church was Celtic in origin it may be presumed that the Celtic type of monachism prevailed amongst the Christians in this country after the Saxon conquest. Whether it followed the distinctive practice of Irish monasticism in regard to the position of the abbot and the subject bishops may perhaps be doubted, as this does not appear to have been the practice of the Celtic Church of Gaul, with which there was a close early connection.
It has usually been supposed that the Rule of St. Columbanus represented the normal life of a Celtic monastery, but it has been lately shown that, so far as regards the Irish or Welsh houses, this Rule was never taken as a guide. It had its origin apparently in the fact that the Celtic monks on the Continent were induced, almost in spite of themselves, to adopt a mitigated rule of life by their close contact with Latin monasticism, which was then organising itself on the lines of the Rule of St. Benedict.[8] The Columban Rule was a code of great rigour, and "would, if carried out in its entirety, have made the Celtic monks almost, if not quite, the most austere of men." Even if it was not actually in use, the Rule of St. Columbanus may safely be taken to indicate the tendencies of Celtic monasticism generally, and the impracticable nature of much of the legislation and the hard spirit which characterises it goes far to explain how it came to pass that whenever it was brought face to face with the wider, milder, and more flexible code of St. Benedict, invariably, sooner or later, it gave place to it. In some monasteries, for a time, the two Rules seem to have been combined, or at least to have existed side by side, as at Luxeuil and Bobbio, in Italy, in the seventh century; but when the abbot of the former monastery was called upon to defend the Celtic rule, at the Synod of Macon in A.D. 625, the Columban code may be said to have ceased to exist anywhere as a separate rule of life.
For the present purpose it will be sufficient to consider English monasticism from the coming of St. Augustine at the close of the sixth century as Benedictine. There was, it is true, a brief period when in Northumberland the Celtic form of regular observance established itself at Lindisfarne and elsewhere. This was due to the direct appeal made by King Edwy of Northumbria to the monks of Iona to come into Northumbria, and continue in the North the work of St. Paulinus, which had been interrupted by the incursions of Penda. Iona, the foundation and home of St. Columba, was a large monastic and missionary centre regulated according to the true type of Celtic monachism under the abbatial superior; and from Iona came St. Aidan and the other Celtic apostles of the northern parts. In one point, so far as the evidence exists for forming any judgment at all, the new foundation of Lindisfarne differed from the parent house at Iona. At the Northumbrian monastery the bishop was the head and took the place of the abbot, and did not occupy the subordinate position held by the bishops at Iona and its dependencies.