The place to begin is with ancient Christianity in Great Britain. There is evidence it goes as far back at the second century. It contained Celtic and Roman strains. It was an integral part of Western Christendom. It is of course also a history of conflict and fractiousness — no less a figure than Wycliffe reminds us of this. But it is a continuous history nonetheless. Part of Anglican identity is looking back and remembering this fact, for example among the early Anglo-Catholics of the 19th century. Let us relate this fact, now offered as a claim, to the mark of the Church of oneness in the Creeds.
At this point I want to introduce the epistemological crisis, a concept from the moral philosopher Alasdair MacIntyre. It depends on the prior notion of a tradition, a stream of thought and practice that coheres around a shared narrative, pointed toward a shared telos and enacted by shared virtues. The idea is not necessarily religious, but works for a religious community too. Within the boundaries formed by these features a tradition is a continuing argument. Occasionally, however, a tradition runs into a major challenge to its very coherence, indeed to its existence, from without. Its truths are called into question in a basic way, and the tradition summons its collective resources to offer an answer. Christianity was such a challenge for ancient imperial pagan culture, and the latter was not up to the task.
The ancient church in the British Isles encountered three epistemological, spiritual, political, and social crises, and in response to each it had to give a continuous answer. The first was of course the Reformation, and the major artifact of the era for us as Anglicans is the Book of Common Prayer. In fact the most concise and compelling answer to the question What is an Anglican? is a prayer book Christian. Through it, British Christians heard and absorbed Reformation doctrine in a devotional mode.
In other words, using the prayer book in an ancient church is a factual, pragmatic way to say that we work out our identity between Protestant and Catholic. And of course the ensuing centuries, after the bloodletting of Henry, Mary, and Elizabeth in the 16th and Charles and the Puritans in the 17th, would reach back to retrieve or reject, to reconstrue and redefine: the great Anglo-Catholic and evangelical revivals of the 19th century are great examples. But one can still see the inheritance of this conflict amid agreement in Western Christianity in the styles of various parishes, however they recall the implications of their liturgical choices.
High and old may be the more venerable designators for Anglican churches, but the more prominent, and more conflictual, is what they make over the spiritual-epistemological crisis, since the 17th and 18th centuries, that is modernism.
Read it all.