More may be added to the earlier biography.
Jacob intermittently served as an attorney in the courts of common pleas and Chancery, numbering among his clients not only regular associates like Sir Thomas Stawell† and Sir William Palton*, but also a range of other leading south-westerners, including Sir Thomas Carewe and successive sheriffs of Somerset and Dorset, for whom he acted as receiver of writs and also fulfilled other functions.
It was evidently in connexion with Jacob’s acquisition of his property in Petherton, Bridgwater and Wembdon that he and Alexander Hody* in the summer of 1447 unsuccessfully sued Roberta, the widow of James Hanyngton of North Petherton for the return of a chest of muniments, at least one of which recorded the settlement of the remainder of the lands on Alexandra, the wife of one of the several John Sydenhams alive at that time.
The date of Jacob’s death remains uncertain, but it occurred prior to the autumn of 1470, when his widow was suing a group of men from Bradford for a trespass.