High Quality Content by WIKIPEDIA articles! Sir David Mathew (1400–1484) (or Welsh: Daffyd) was a Welsh knight. He was Lord of Llandaff, Seneschal of Llandaff Cathedral, one of the ten Great Barons of Glamorgan, and a Marcher Lord. He was one of the most distinguished men of his age and a zealous supporter of the Yorkist cause. After he saved the life of King Edward IV at the Battle of Towton, on Palm Sunday, 29 March 1461, he was appointed Grand Standard Bearer of England.