Dear John Mark,
Quote:Council of Chalcedon - when did the effects of this council begin to be felt in Britain if at all and was there a change in "Orthodoxy"?
Arrival of St Augustine of Canterbury in 597AD - was Britain significantly less Orthodox after this point?
1066 and the Norman invasion - How long did Orthodoxy last before being replaced by Catholicism?
I'm unsure whether this conceptualisation will help you, since to see 'Catholicism' and 'Orthodoxy' as somehow separate at this period is to read back into the contemporary record distinctions that would have made little sense to contemporaries.
Bede makes pretty clear the differences made by St. Augustine's arrival, and there is a kind if romanticism (to which I, myself, am terribly prone) which sees the 'Celtic' Christians of the old Roman dispensation as somehow more 'authentic' and 'Orthodox' than the new Roman dispensation which came with St. Augustine; of course, both were Roman dispensations, and the second one is part of the answer to your questions: Augustine brought the English Church 'up to date' with the doctrinal and Christological developments which had taken place since 410 A.D.. To see this as somehow more 'Catholic' may be to miss some essential points - tempting though it is.
England was always pretty close to Rome, and to see the Conquest as replacing Orthodoxy with Catholicism is again, I suspect, to fall for what might be called a myth that is 'wrong but romantic' in preference to the 'right but repulsive' reality, which is that Harold II was as loyal a Christian as William the [censored], but the latter managed to convince Rome that he had a better claim to the throne than Harold (he certainly had no worse a claim). The posthumous attempt to see Harold as a champion of Orthodoxy, based on the fact that one of his daughters married a Grand Duke of Kiev, is a pretty piece of myth-making, to which, again, I am rather attracted, but most serious historians would not subscribe to it. The English Church was already using the filioque
clause in the creed in Bede's time - did that make Bede a Catholic?
Bede would have been shocked at the question. His history is a triumphant account of how Catholic Orthodoxy came to dominate these islands - he would have been baffled at the distinction we would seek to draw between those two words; and perhaps he would not have been wrong?
I don't know of a comprehensive list of pre Chalcedon British saints, and like you, would be interested to hear of one.
In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins. (1 John 4:10)