Sounds interesting, BUT,
“Ardrey, an amateur historian who works as an advocate in Edinburgh”
If he was from France, Arthur would be French, Italy, he would be Italian - I see some chauvanism here.
I think Arthur was a Romano-British Warlord “Dux Bellorum” (Chief of Battles)who fought the Saxons sometime after the Romans pulled out of Britain.
The name Arthur appears related to a Latin word for “bear”, Prior to his activities in the late 5th and early 6th Century, Arthur was a relatively rare name. After that time, every other Celt in Britain was naming his kids after him. I think the best sources are Nennius and Gildas.
Nevertheless, in my efforts to read as much as possible about the REAL Arthur, not the fantasy of Sir Thomas Mallory, I must read this book.
ping for later
Ditto on the “bear” — Ursa is Latin for bear, Arth (Rth) is Welsh (not Scottish, although it might be Pictish, which appears to have been P-Celtic like Welsh and Cornish) for bear, making Arthursa a macaronic name meaning bear.
Geoffrey of Monmouth preserved a load of stuff about Arthur and other old lore. Gildas never once mentions Arthur by name, but does refer to one or more of Arthur’s Twelve (legendary) battles. Apparently there may have been some bad blood for Gildas, who was related to one of Arthur’s rivals (whoever Arthur was).