It can be little short of certain that St. Patrick must have passed through Clane on his way from Tara to Naas. If he did, one wonders how he felt on finding a Christian Monastery already there on his arrival. The monastery in Clane is said to have been established by St. Ailbe, Bishop of Emly, a fellow Roman (Ailbeus) who, along with Aidan of Ardmore, is believed to have preached Christianity in Ireland before the arrival of Patrick in 432. It is a singular fact that there is no tradition of St. Patrick having been in Clane and there are no establishments, even to holy wells, attributed to him. This, although he is credited, with a degree of certainty that is quite exceptional, with having established a church five miles to the North of Clane at Dunmuraghill beyond Staplestown. Predictably, the Annalists give a later date for Ailbe's foundation at Clane. One is cautioned however, to treat such proposed dates with suspicion, as the importance of establishing the primacy of Patrick was clearly seen by the Armagh lobby as the best basis for maintaining the primacy of the northern Archdioceses in their bitter struggle with Dublin.

Nothing remains of the ancient Celtic monastery in Clane, neither stone church nor round tower, if ever such existed. If stone buildings did exist, it has been suggested that the stone would likely have been removed for the Franciscan Abbey established by the Norman invaders in 1258. If indeed they had no stone buildings, they must surely have regretted the fact when Clane was sacked and plundered bv the Danes in 1035, some twenty one years after 1014 when history, undoubtedly showing a Munster prejudice on this occasion, ironically recorded that Brian Boru had rid the country of the Norse in the celebrated Battle of Clontarf. It is believed that the site of Ailbe's monastery is that where the Abbey now stands and which was formerly the ruins of the old Protestant church, which were there for one hundred years, crowning the village green, following the building of the new church at Millicent. That is was an important monastery, there can be little doubt. In 1162 it was the setting for a general synod of the Church, attended by 26 bishops and a large number of abbots. Armagh was represented by Gelassius, and Dublin by St. Lawerence O'Toole, who had recently been appointed Archbishop. It was at the Synod of Clane that one of the final bulwarks was added to the Primacy of Armagh when it was enacted that nobody could be a lector in any part of Ireland - taken to be the equivalent of the modern Professor of Theology - who had not been educated at Armagh. One wonders had things gone differently would Dermot Ryan and not Tomás Ó Fíach be Cardinal today. One wonders also what the people of Clane thought of Archbishop Gelassius whom history would suggest was suffering from advanced paranoia, for his whole life was governed by a fear of being poisoned by his enemies, and he took no food or drink except what he personally milked from his own white cow which was led behind everywhere he went.