I would also add Bryan Sykes “Blood of the Isles” to the reading list after Oppenheimer. Both excellent reads... from
strongly opinionated Oxford academics.
As always, truth is not absolute but if you stop at the blandishments from that Geoff bloke off of Monmouth or that Walter Scott geezer, let alone whatever bollocks us English come up with, then it's downhill all the way to ... erm the present day.