Now, according to many historians, the King Arthur that actually existed was based upon a Roman Cavalry man several hundred years after Augustus who fought the Saxons in the area of Wales and London. He repelled the Saxons and Unified the lands in that area.
However, some of his legends were mixed up on the main continent with those of a Spanish General named Maximus (yes, probably got the idea for the movie Gladiator off this type of character and mixing it with Comodos's death). Others were mixed with some Irish folklore...
But overall, many historians agree that Arturius was the one that the basic legend of Arthur comes from. Now we see Arthur fought off the Saxons...but seeing modern day England...
If Arthur were to return...would he attempt to destroy the Royal House, Conquer Wales, rejoice with those that are there? Or would he do something different?
I personally think he'd go insane and crazy trying to figure out where all his people had vanished to and try to conquer the British Isles from EVERYONE there...