In 1258 and 1259, Boniface was a member of the Council of Fifteen, which conducted business for Henry III under the Provisions of Oxford. This Council consisted of the earls of Leicester, Gloucester, Norfolk, Warwick, Hereford, the Count of Aumale, Peter of Savoy, John fitzGeoffrey, Peter de Montfort, Richard Grey, Roger Mortimer, James Audley, John Maunsell, Walter de Cantilupe, Bishop of Worcester as well as Boniface. One of the actions of this council was to send the Lusignans into exile. In April 1260, Boniface worked with Richard of Cornwall to broker a peace between King Henry and Prince Edward.