Thomas Cook, who represented Marlborough in 1399, may have been William’s father,The Commons 1386-1421, ii. 646. but otherwise nothing is known about his family. William witnessed the will of William Berughdon, another burgess of Marlborough, made in the autumn of 1422. PCC 55 Marche (PROB11/2B, f. 199v). Of some standing in the borough, he served as mayor from Michaelmas 1425, and while in office was elected to the Parliament held at Leicester in the following year. Precisely when he was made coroner of Marlborough is not known, but he was still occupying that post at the time of his death; the sheriff of Wiltshire was instructed to arrange for the election of a replacement on 12 July 1445, although how recently Cook had died is not revealed.CCR, 1441-7, p. 264.
