https://en.wikipedia.org/wiki/Early_centers_of_Christianity#...
in my opinion, there were likely christians throughout the empire roughly simultaneously due to the strength of roman trade routes.. as to which places embraced the faith nationally, is a different story..
also: angles & saxons arrived to the british isles after the roman empire.. prior to this the local population was mainly celtic..
another interesting tidbit is that Emperor Constantine was crowned emperor in York before beginning his journey back to take the empire where he famously had a vision of the christian cross.. granted this is a few hundred years later, but still, very early, before the the british isles were settled by Anglo Saxons, and highlights how interconnected the british isles were with the rest of the empire in those days..
http://historyoftexttechnologies.blogspot.com/2017/04/the-dr...
https://en.m.wikipedia.org/wiki/Ruthwell_Cross
A professor had us all memorize a passage from that poem which I can still recite. It’s quite eerie, and a fascinating look at how cultures adapted to Christianity and adapted Christianity to their needs in turn.
"No one ever calls on me to "broadcast" or do a postscript. Yet I suppose I know better than most what is the truth about this "Nordic" nonsense. Anyway, I have in this war a burning private grudge... against that ruddy little ignoramus Adolf Hitler ... Ruining, perverting, misapplying, and making for ever accursed, that noble northern spirit, a supreme contribution to Europe, which I have ever loved, and tried to present in its true light. Nowhere, incidentally, was it nobler than in England, nor more early sanctified and Christianized."