 The fourth chief, Sir William Galbraith of Buthernock, married a sister of "Black Comyn" who was head of the most powerful family in Scotland at the time.Sir William, however, sided against the Comyns when he had a part in the rescue of the boy king Alexander III from Comyn's control.Ultimately Sir William rose in power to become one of the co-Regents of Scotland in 1255.