The King found important positions for all of them; William was soon married to a great heiress, Joan de Munchensi or Munchensy (c. 1230after 20 September 1307), the only surviving child of Warin de Munchensi, lord of Swanscombe, and his first wife Joan Marshal, who was one of the five daughters of William Marshal, 1st Earl of Pembroke and Isabel de Clare, 4th Countess of Pembroke "suo jure".