Sir William Portman, 6th Baronet (5 September 1643 – 18 March 1690) FRS was an English politician who sat in the House of Commons between 1661 and 1690. Portman was the son of Sir William Portman, 5th Baronet and his wife Anne Colles, daughter of John Colles. He inherited the baronetcy on the death of his father in 1646. In 1661, Portman was elected Member of Parliament for Taunton for the Cavalier Parliament and held the seat until 1679. In 1679 he was elected MP for Somerset where he sat until 1685. He was then elected MP for Taunton again, and held the seat until his death in 1690. Portman married three times but died without issue and the baronetcy became extinct. Life He was the eldest son of Sir William Portman, 5th Baronet (1610–1648) of Orchard Portman, by Anna, daughter and coheiress of John Colles of Barton. The father was returned for Taunton to both the Short and Long parliaments of 1640, but was disabled, as a royalist, to sit on 5 February 1644. On his death in 1648, William succeeded him as sixth baronet. He matriculated at All Souls' College, Oxford, 26 April 1659, and at the Restoration of 1660 was made a Knight of the Bath. He represented Taunton in parliament from 1661 until 1679, and from 1685 till his death. From 1679 to 1681 he sat for the county of Somerset. Apart from Sir Edward Seymour, he was accounted as influential a tory as any in the west of England. He was a strong ‘abhorrer’ during the exclusion crisis in Charles II's reign, and while attending parliament in May 1685 he received a mysterious warning of the Duke of Monmouth's impending insurrection in the west. He directed the search of post-coaches in the neighbourhood of Taunton, in the hope of intercepting treasonable correspondence, and took an active part in investigating the causes of disaffection, and later on in organising the militia. After the battle of Sedgmoor (6 July 1685) Portman, with the Somerset militia, formed a chain of posts from Poole to the northern extremity of Dorset, with a view to preventing Monmouth's escape. On 8 July he and Lord Lumley captured the fugitive Duke near Ringwood in the New Forest, and did not trust him out of their sight until he was delivered safe at Whitehall. In November 1688 Portman joined the Prince of Orange