John Seymour, 4th Duke of Somerset
…3rd Marquess of Hertford (before 1646 – 29 April 1675) was an English peer and MP. He was a younger son of William Seymour, 2nd Duke of Somerset, and Lady Frances Devereux. He was the only one of the second duke's sons still alive when his father died and the title descended to his six-year-old nephew, William. In 1661…