https://en.wikipedia.org/wiki/Alan_fitz_Flaad

Alan fitz Flaad was a Breton knight, probably recruited as a mercenary by Henry I, son of William the Conqueror, in his conflicts with his brothers.[1] After Henry became King of England, Alan became an assiduous courtier and obtained large estates in Norfolk, Sussex, Shropshire, and elsewhere in the Midlands, including the feudal barony and castle of Oswestry in Shropshire.[2][3][4] His duties included supervision of the Welsh border.[5] He is now noted as the progenitor of the FitzAlan family, the Earls of Arundel , and the House of Stuart,[6] although his family connections were long a matter of conjecture and controversy.