William de Aldeburgh was the son of Ivo de Aldeburgh, a prominent soldier in the Scottish wars. Ivo was appointed Sheriff of the Three Lothians by Edward I in 1305 and warden of Roxburgh Castle under Edward II, and was one of the party sent to negotiate with Robert the Bruce in 1326/7. After Ivo's death in the reign of Edward III, William received royal confirmation to hold a number of castles and manors, in Galloway and Broxmouth, which had been granted to his father by Edward Balliol. Like his father, William was a close ally of Edward Balliol, and was one of the latter's close companions during his exile. Balliol granted him further lands in addition to those already granted to Aldeburgh's father, including the baronies of Kirkanders, Balmaghie, and Kells.