 He worked on several legal commissions in this period, many in his native Lincolnshire and surrounding counties.One commission in particular was designed to help the Despensers gain the Lordship of Gower against John Mowbray and his allies.It was Malberthorp who, in the king's name, passed a judgement of death over the rebellious Thomas of Lancaster, after Lancaster's defeat at the Battle of Boroughbridge.