The consensus view is that "Arthur" was probably a Romano-British warlord who vainly attempted to hold back the tide of Anglo-Saxon migration. His fabulous castle of Camelot, his wife Guinevere, his sword Excalibur, his deceitful nephew Mordred and his confidant Merlin are all regarded as no more than figments of the imagination. It is assumed that behind the glorious facade of the "Once and Future King" is nothing but moonshine.
This negative view of Arthur is not a recent phenomenon. Arthur as we know him dates from 1136 AD and the publication in Latin of Geoffrey of Monmouth's History of the Kings of Britain. In this history, which he translated with some elaboration from an earlier work in Welsh (the Brut Tysylio), Arthur not only fights against the Saxons but also crosses over to Europe and defeats the Romans. These feats seemed credible enough until in 1552 Polydore Vergil, historian at the court of Henry VIII, pointed out that for Arthur to have fought both the Romans and Saxons he would need to have lived for 200 years. After this observation both Arthur and Geoffrey's History lost much of their credibility.
Yet there is a simple answer to Vergil's conundrum. The Brut Tysylio was probably written in Brittany at the time of King Athelstan, who ruled most of Britain from 925 to 940. Brittany was then home to a large population of Britons who had moved there in several waves centuries earlier. The first of these was in 383 when a British king, Magnus Maximus, took a large army to Gaul to assert his claims to the Roman Empire. His eldest son, Arthun, led the British expeditionary force, defeating and killing Gratian, the Emperor of the West, and installing his father in his place. In 388 Theodosius, Emperor of the East, defeated the smaller army of Maximus in the battles of Poetovio and Sisica. Arthun, who disappeared after the second of these battles, may have escaped back to Britain.
According to Welsh records, a second mass migration to Brittany took place in the sixth century when the island of Britain was gripped by a terrible plague known as the "Yellow Death". Prior to these events a Welsh king, Athrwys, the son of Meurig, inherited the kingdom of Glamorgan and was elected Pendragon of Britain. He is said to have won the Battle of Baidan, which was fought on a site in South Wales still marked on the Ordnance Survey as "Mynydd Baidan". It would seem that the career of Athrwys was later confused with that of Arthun giving rise to the heroic King Arthur of legend.
The second stone found by Wilson and Blackett is without doubt that of King Arthur II, son of Meurig. The first was probably that of Arthur I, son of Magnus Maximus. It seems a shame to me that unlike the slate from Tintagel these stones have so far been ignored.
Adrian Gilbert is the co-author, with Alan Wilson and Baram Blackett, of `The Holy Kingdom: the quest for King Arthur' (Bantam Press, pounds 19.99)