Well, different people use history for their own different purposes. Rome’s version of history, the one where the fullness of The Church is found in one man and all the local dioceses and national or regional churches are merely franchises of the Roman home office is a version Roman has, until quite recently, been peddling ever since the Great Schism. Now, because it is so intent on reunion with Holy Orthodoxy, it no longer presses that definition of The Church.
As for the Celtic Church, as one of the articles on the blog points out, monasticism in England, Ireland, Scotland and Wales was distinctly Eastern. It bore little resemblance to Western Benedictine style monasticism. The ties of the monks at Iona and elsewhere with the monks in the Desert between Egypt and Jerusalem is very well documented. The Conciliar/Synodal system prevalent in the British Isles before the arrival of Augustine at Canterbury, a system recognizable as thoroughly Eastern and thus Catholic stands in stark contrast to the pyramidal system set up under Rome’s local managers.
I am not saying, AM, that I am convinced for one minute that any form of modern Anglicanism is that ancient Celtic Catholicism. In fact, I think it is at best a pale imitation, but it has been my experience that Episcopalians/Anglicans who come to Orthodoxy have a much easier time and come to understand Orthodoxy and its mindset much, much quicker than converts from Roman Catholicism. This is counter intuitive because of course Latin theology and Orthodox theology are pretty much the same, but the mindsets are 180 degrees off each other. The way we live the Faith and respond to it are opposite. The Anglicans seem to get that almost immediately. It takes Latins as long, sometimes longer, as Evangelicals to understand the Orthodox “phronema”. There is something of a vestigial Orthodoxy lurking there in Anglicanism. I can only assume its a reflection of a long past Eastern way of looking at The Faith.
Our local Orthodox parishes here are extremely parochial and don't welcome 'outsiders'. It never even crossed my mind to consider it, even though I have Orthodox (Greek) friends they have never invited me to church. The Melkites (nominally under the Roman rite) are far more welcoming, but their parish is up the other side of Alpharetta.
Your Roman 'version of history' is just a wee bit exaggerated, don't think that's fair. We'll never get the two lungs of the Church back together with that attitude!
I know it wasn’t until AD 664 at the Synod of Whitby Abbey that any Churches in the British Isles pledged fealty to Rome. The great saints Patrick and Columba were surely very Catholic, but not, except by apocryphal history, Roman Catholic.