He was much-liked at court, and as a result was appointed to politically sensitive cases, such as the 1444 commission to investigate charges of treason against Thomas Carver, and a 1447 commission directed at members of the household of Humphrey, Duke of Gloucester. In 1450 he was himself indicted for treason in the aftermath of Jack Cade's rebellion in Kent, but before any sort of commission could take place he was murdered. While travelling to meet with Richard of York with his son, Sir Thomas Tresham, the pair were assaulted by a group of local men with whom Tresham was in a property dispute. William was killed, and Thomas escaped injured.
