I did read somewhere (it might have been Paul Colinvaux) that once the English aristocrats and their professional war bands were thrown out of France, something like the War of Roses was inevitable. I don't know if it would have been politically possible to focus on another target than France.
On earlier threads, it was pointed out there was a good chance the American horse might be not as easily domesticable as ours. But even if it wasn't, as prey might it supplement other prey, and mean a slightly denser population of hunters?
Thanks for this good depiction of how Britain fares. I do like the bit about Viroconium of the Conferences. The tripartition is interesting - good joke of Lucius. Any chance of a map?