The Last Kingdom was excellent...I would fully recommend it.
the Arthur trilogy....as he puts it in his Author's Notes at the end of the first book (the Winter King), there is a clear progression from the ancient Celtic cauldron tales involving magic to the oral traditions which spread the tale into all of Britain and Normandy....the Cauldron morphed into the Grail and over the centuries various additions were added to the story, such as Lancelot (who in these books is painted as a complete buffoon) and many of the various characters we take for granted today...then of course there was also the Church, who used the oral tales for its own ends. So Cornwell basically says, I've used some of the oldest stuff and sprinkled in some of the new. But he cleverly, as a literary device, has as the narrator an aging monk who is writing the truth in Saxon, his patron Queen, Igraine, who is promptly handing his scrolls over to her own scribe for translation (and her own embellishments), and the Bishop who suspects the monk of something close to heresy, and is teaching his own catamite accolyte to read both languages so he can use the tales for his own ends.
As usual Cornwell displays (and this is a plus) his characters' disdain for religion and so there is precious little pontification other than that coming from individuals who always have their own agenda.
These are easily his most "fantasy" oriented books (other than the standalone Stonehenge novel), involving as it does Merlin and various druids, although the magic is never definitive and as often as not plays on the superstitions of the characters more than the genuineness of the spells.
all of which is a long way of saying its only as historical as oral tradition can be.
