William Seymour, 2nd Duke of Somerset was the great-grandson of Edward Seymour, 1st Duke of Somerset (c.1500-1552), the uncle of King Edward VI and Lord Protector of England. Seymour made a secret marriage at Greenwich on 22 June 1610 to Arbella Stuart (d.1615), daughter of Charles Stuart, 1st Earl of Lennox and Elizabeth Cavendish. Arbella was thirteen years his senior, and King James I disapproved of the marriage as the union of two potential Tudor pretenders to the throne, who were respectively fourth and sixth in line, could only be seen as a threat to the ruling dynasty. As a result, William was condemned to life
Charles Seymour, 6th Duke of Somerset Duke of Somerset, aged 16, inherited the Dukedom of Somerset from their father's childless first cousin, John Seymour, 4th Duke of Somerset (1629–1675). However, the 5th Duke did not inherit the unentailed Seymour estates, including the family seat of Wulfhall and other Wiltshire estates, and much of the lands of the feudal barony of Hatch Beauchamp in Somerset, which were bequeathed to the 4th duke's niece, Elizabeth Seymour, wife of Thomas Bruce, 2nd Earl of Ailesbury (1656–1741). In 1660, following the Restoration of the Monarchy, the 4th duke's own father, a Royalist commander in the Civil War, had been restored