William the Bastard (his name at the time ; the "Conquerer" bit was only added a few generations later) was sufficiently far back that everyone in Britain is related to him by multiple routes. While both Guillame Le BatÃrd and Charlemagne were of Germanic descent, I think Charlemagne's antecedents came out of the forests of Germania (as the Romans called it), probably under the impetus of invading Tatars from the east. Guillame Le BatÃrd, on the other hand, came from a more Nordic stock, and his immediate ancestors were involved in stealing land from Charlemagne's descendants. Probably there were indirect relationships, but by means of political marriages, not blood.
Nasty bunch of robber barons, the lot of them. Your Welsh antecedents were probably no better. Ditto for my antecedents in Britain and Ireland.
Enjoy your castle. I'll enjoy central heating and negligible death duties.
Oops, not logged in ; fixed.