Bonhomie or the keeping of promises? St Augustine of Canterbury: a view trans Sabrinam

My colleague Fr Mark has a fascinating post here on the subject of St Augustine of Canterbury (he has only an optional memoria here in Wales) meeting the Celtic (Welsh or Romano-British) bishops at Aust in what is now Gloucestershire.
Our information on this encounter comes from Bede's History of the English Church and People. The first meeting could be characterised as difficult. The atmosphere seems to have been one of mutual incomprehension and suspicion and, despite a healing miracle and a recognition that Augustine's teachings and credentials were impeccably orthodox, there was a pronounced reluctance on the part of the 'British' bishops to abandon ancient customs without the consent of their own people.
The Celtic 'patrimony' (although Latin in origin - and, of course, in its liturgy and doctrine - these were no anachronistically proto-protestants or 'Anglicans' in embryo) had developed organisationally and in many of its customs in geographical and ecclesiastical isolation from the rest of the Western Church following the collapse of the Roman Empire.
Interestingly, one of the sticking points seems to have been Augustine's insistence that the Celtic Christians join him in the mission to convert the English, who for the 'Welsh,' were the hatred pagan invaders and despoilers of Roman Britain.
But if the first conference had gone badly, the second meeting (somewhere in what used to be called Flintshire) was a complete disaster. The British bishops and their advisors had taken counsel from a 'wise and prudent' hermit. This is St Bede's account:

"This being decreed, there came, it is said, seven bishops of the Britons, and many men of great learning, particularly from their most celebrated monastery, which is called, in the English tongue, Bancornaburg, and over which the Abbot Dinoot is said to have presided at that time. They that were to go to the aforesaid council, be-took themselves first to a certain holy and discreet man, who was wont to lead the life of a hermit among them, to consult with him, whether they ought, at the preaching of Augustine, to forsake their traditions. He answered, "If he is a man of God, follow him."— "How shall we know that?" said they. He replied, "Our Lord saith, Take My yoke upon you, and learn of Me, for I am meek and lowly in heart; if therefore, Augustine is meek and lowly of heart, it is to be believed that he bears the yoke of Christ himself, and offers it to you to bear. But, if he is harsh and proud, it is plain that he is not of God, nor are we to regard his words." They said again, "And how shall we discern even this?" – "Do you contrive," said the anchorite, "that he first arrive with his company at the place where the synod is to be held; and if at your approach he rises tip to you, hear him submissively, being assured that he is the servant of Christ; but if he despises you, and does not rise up to you, whereas you are more in number, let him also be despised by you."

They did as he directed; and it happened, that as they approached, Augustine was sitting on a chair. When they perceived it, they were angry, and charging him with pride, set themselves to contradict all he said. He said to them, "Many things ye do which are contrary to our custom, or rather the custom of the universal Church, and yet, if you will comply with me in these three matters, to wit, to keep Easter at the due time; to fulfil the ministry of Baptism, by which we are born again to God, according to the custom of the holy Roman Apostolic Church; and to join with us in preaching the Word of God to the English nation, we will gladly suffer all the other things you do, though contrary to our customs." They answered that they would do none of those things, nor receive him as their archbishop; for they said among themselves, "if he would not rise up to us now, how much more will he despise us, as of no account, if we begin to be under his subjection?" Then the man of God, Augustine, is said to have threatened them, that if they would not accept peace with their brethren, they should have war from their enemies; and, if they would not preach the way of life to the English nation, they should suffer at their hands the vengeance of death. All which, through the dispensation of the Divine judgement, fell out exactly as he had predicted."  [from Book Two, Chapter 2]

Lessons drawn from history and legend are notoriously subjective and are probably best left unmade. Over the centuries this particular episode has one of great comfort both to romantic Celtic ecclesiastical separatists and those who have a more generally instinctive anti-Roman theological bias, although the point is well made in Bede's account that the 'bottom line' of the mission entrusted to St Augustine from Pope Gregory was one of evangelism at all costs and the conversion of an entire land and all its peoples.

Me? Risking all the dangers of interpretation, I would prefer to trust an invitation from someone who, whilst respecting elements of our patrimony and, in fact, protecting and preserving them, was nevertheless well aware of the great authority entrusted to him, than I would all the false courtesy and bonhomie of those who fail to keep their promises.

Now what could I mean by that?

St John's Church at Aust