Charles Seymour, 6th Duke of Somerset the pride of birth and rank amounted almost to a disease". Charles was the second son of Charles Seymour, 2nd Baron Seymour of Trowbridge (died 1665), of Marlborough Castle in Wiltshire, by his wife Elizabeth Alington (1635–1692). The 2nd baron was (in a junior line) a great-great-grandson of Edward Seymour, 1st Duke of Somerset (executed 1552), brother of Queen Jane Seymour, uncle of King Edward VI and Lord Protector of England. Charles was educated at Harrow School and Trinity College, Cambridge, where his portrait by Nathaniel Dance-Holland survives in the College's collection. In 1675, Charles's elder brother Francis Seymour, 5th
Charles Seymour, 6th Duke of Somerset of Hertford (1684–1749) had produced a son of his own, Lord Beauchamp (d.1744), who had predeceased him without progeny, and thus he had only a daughter and sole heiress Lady Elizabeth Seymour, who in 1740 had married Sir Hugh Smithson, 4th Baronet. Before the death of the 6th duke in 1748, it had thus become apparent that the dukedom of Somerset would devolve by law onto an extremely distant cousin and heir male, the 6th duke's 6th cousin Sir Edward Seymour, 6th Baronet (1695–1757) of Berry Pomeroy in Devon and of Maiden Bradley in Wiltshire, who in fact represented the