This is one of the finest popular histories I have ever read. Whether it is a book about 5th and 6th century British history using Arthur as a organizing principle, or a book about the "real" Arthur using 5th and 6th century history as a backdrop, this book is wholly convincing concerning the reality of Arthur and the historical context in which he lived. The book may actually be too good. The most convincing evidence it cites -- the so-called British Easter Annals -- appear to have been called into question by subsequent scholarship; and the link between Arthur and Mount Badon is not quite as convicing as it seeme to be when Alcock wrote the book. In short, this masterpiece needs updating. But a masterpiece it is. No one who reads this book with any care can fail to come away from it without a vastly improved understanding not only of the British dark ages, but of the nature of historical evidence, scholarship, and truth. This is a great book.
After posting my original comments, I would still rate this book a "5." But there has been a lot of "water over the dam" since Alcock wrote, and the book was so good it deserves an update. For example, Sykes wonderful "Saxon, Celt, Viking" does a genetic analysis of Great Britain (the technology was not available when Alcock wrote" demonstrating that about 2/3 of what is now England is "Celtic" by the male line and over 3/4 by the female line. So we know there was not a "Germanic replacement," something Alcock suspected but could not prove. And Alcock himself revised his position somewhat:
"In the 'Mortimer Wheeler Archaeological Lecture', given before the British Academy on 13 October 1982, Professor Alcock makes the following statements, re-assessing his position on Arthur's historical reality: "The Arthur of history is another matter. Whatever value my essay in souce-criticism may have had in 1971 [see above], it has largely been swept away by the studies of Drs Dumville, Miller and the late Kathleen Hughes. Largely, I think, but not entirely; and certainly the debate is too large to enter into here. At present, however, my position on the historicity of Arthur is one of agnosticism". While this is not a full recantation, Alcock certainly steps far back from his earlier position."