He was a Magna Carta baron.

He was in the Crusade of 1188-1192, under Richard Coeur de Lion, King of England. One of his fellow crusaders was Robert, third Earl of Leicester, afterward his father-in-law.

Saer de Quincy, 1st Earl of Winchester (1155 – 3 November 1219) was one of the leaders of the baronial rebellion against King John of England, and a major figure in both Scotland and England in the decades around the turn of the twelfth and thirteenth centuries.