The chronicler Orderic Vitalis states that Edwin's reason for revolting was that the proposed marriage between himself and one of William's daughters had not taken place, but another reason probably included the increasing power of William fitzOsbern in Herefordshire, which affected Edwin's power within his own earldom.
Kronikøren Orderic Vitalis beskriver, at årsagen til at Edwin gjorde oprør var, at det foreslåede giftemål mellem ham og en af Vilhelms døtre ikke havde fundet sted, men andre årsager inkluderede sandsynligvis William FitzOsbern øgede magt i Herefordshire, der påvirkede Edwins magt i hans eget jarldømme.