Ambrosius Aurelianus ping!The reason I looked for information on the dating of Offa's Dyke was that I wondered if anyone had ever scientifically dated it. This occurred to me only because I'd watched program one (of three) on this History Channel dvd about King Arthur.
Dunno why it never struck me before, considering that Wat's Dyke used to be considered newer than Offa's Dyke until someone actually scientifically dated it, and the Wansdyke which runs west to east postdates the Roman withdrawal and was attributed to Woden by the Saxon invaders.
Since the 1960s it has been known that "dark age" trade with the Byzantine empire was detected at Glastonbury, and in the 1980s this was also found to be the case at Tintagel. I'll go right out on a limb and say, the composite character called King Arthur owes part of his legend to this Ambrosius Aurelianus, and that Ambrosius (who left his legacy as various post-Roman placenames) and/or his successor constructed the "Offa's" Dyke to protect his Romanized British kingdom from the dozen or so cattle-raiding wannabee kingdoms in Wales, and the Wansdyke to defend against the Saxons.
This dating is a huge breakthrough, although you'd never know it if you read the idiotic quotes I cut out for length.
