Sharp seems to have a conception of English society rather like Gerard Winstanley's, the "Norman yoke" - the division is not so much ethnic (though the descendants of the Norman aristocracy did tend to retain their wealth) as that the Norman *system* survived for centuries. Perhaps William Morris knew about Winstanley and the other 17th century radicals? - they weren't common knowledge until people like Christopher Hill and E.P. Thompson wrote about them in the 1960s.