Interesting, thanks for the ping.
My pleasure. Coel of Rheged (”Old King Cole”, literally) was roughly contemporary with Arthur, assuming there was an actual Arthur, and ruled the buffer state between the rest of former Roman Britain and Caledonia (Scotland).
http://www.historyfiles.co.uk/KingListsBritain/BritainRheged.htm
I’m currently convinced that “King Arthur — The True Story” by Graham Phillips is basically correct, and that Arthur’s capital was Viroconium (basically, modern Wroxeter). I’m also certain that the Arthurian legends incorporate loads of borrowings, both from medieval France as well as pre-Roman, Roman, and post-Roman Britain.
http://www.grahamphillips.net/books/Arthur.htm