 In May 1205 Cornhill, along with Willam of Wrotham, was given custody of one of three dies for the mint at Chichester, but in July the king gave Cornhill's custody to Simon of Wells, the Bishop of Chichester.Cornhill was constable of Rochester Castle in 1215 on behalf of its then holder Stephen Langton, archbishop of Canterbury.He opened its gates to William d'Aubigny and his troops, whom the barons rebelling against King John had sent to the castle to hold it against the King.