He was born on 30 March 1649 at Lytchett Matravers, near Poole, to Thomas Trenchard of Wolverton (1615–1671), and his wife Hannah née Henley (d.

He associated himself with those who proposed to exclude the Duke of York from the throne, and attended some of the meetings held by these malcontents.

Again he entered parliament, but he took no active part in the Revolution of 1688, although he managed to secure the good will of William III.

He and the government incurred much ridicule through their failure to prove the existence of a great Jacobite plot in Lancashire and Cheshire in which they had been led to believe.

[2] On 10 November 1682, he married: Philippa Speke (1664–1743), daughter of George and Mary Speke of White Lackington, Somerset,[1] with four sons and three daughters including: Sir John died on 27 April 1695 at Kensington, London, of tuberculosis[1] and he is buried at Bloxworth, Dorset.