Background
Probably born at Wulfhall, in Savernake Forest, Wiltshire, Seymour was the eldest son of Sir John Seymour of Wulfhall, Wiltshire, and of Hatch Beauchamp, Somerset (c 1395 or 1402, died 20 December 1464) by his marriage on 30 July 1424 to Isabel William or Williams (died 14 April 1486), daughter of Mark William, a merchant and Mayor of Bristol, in some sources given as William Mac William or Williams of Gloucestershire.