Halsall (History/Univ. of York; Barbarian Migrations and the Roman West, 2008) studies the veracity of Arthurian legends.
The author draws on a lifetime of study on the Dark Ages, encyclopedic knowledge of the few known references and detailed notes on area archaeology, and migration. Perhaps the references are the most interesting, not for their content but for the author’s instructions on their use. Citing works written from the sixth to the ninth centuries, including the Venerable Bede and the Anglo-Saxon Chronicle, he searches for hints about Arthur. Of the main works available, Halsall notes that we must understand that chronicle doesn’t necessarily mean factual history. As often as not, their writing was didactic and hagiographic, there to teach a lesson and to laud one particular individual. If there’s little mention of Arthur, is it because the writers didn’t think he was sufficiently important? Or maybe he just didn’t exist. There are records of three historical Arthurs in the sixth century, but that’s the limit of information—just the name. Mere mention of the battle at Mount Badon and the death of an Arthur and a Mordred at the battle of Camlann isn’t sufficient proof of the existence of that idyll. The social, political and economic conditions of the time are better clues to the enigma of Camelot. The author carefully notes that there is little direct mention of Arthur—this doesn’t necessarily prove he never existed, but it doesn’t help prove that he did, either.
One of the most thorough scholarly works on the subject.