• General Notes

  He was a son of Thomas de Ros, 5th Baron de Ros and Beatrice Stafford, daughter of Ralph Stafford, 1st Earl of Stafford. He was also a younger brother of John de Ros, 6th Baron de Ros.
  His older brother died heirless in Pathos, Cyprus during 1394. William was already a Knight and inherited the rank and privileges of his deceased brother. He was first summoned to the Parliament of England on November 20 of the same year. He would reguraly attend sessions till 1413.
  His first assignment from Richard II of England was to join Walter Skirlaw, Bishop of Durham, Henry Percy, 1st Earl of Northumberland and others in negotiating for a peace treaty with Robert III of Scotland.
  Richard favored William with a position in his Privy council. In 1396, William accompanied the King to Calais for his marriage to his second Queen consort Isabella of Valois, daughter of Charles VI of France and Isabeau of Bavaria.
  When Henry of Bolingbroke started his revolt against Richard II, William was among the first to support him. He was present for the abdication of Richard II and the declaration of Henry IV as the new King. He retained his position in the Privy council for the rest of his life.
  He seems to have been a special favourite with the first monarch of the House of Lancaster and was employed him in various civil affairs of great importance. He served as Lord Treasurer of England from 1403 to 1404. He was created a Knight of the Garter in 1403 along with Edmund de Holand, 4th Earl of Kent and Richard Grey, 4th Baron Grey of Codnor.
  William was in charge of investigating the activities of Lollards in Derbyshire, Middlesex and Nottinghamshire from 1413 to his death.
  William was married to Margaret Fitzalan on October 9, 1394. She was daughter to John Fitzalan and Eleanor Maltravers. They were parents to eight children. 
  (Wikipedia)

Details of William's family with Margaret FitzAlan