Dictionary of National Biography, 1885-1900/Heydon, John (d.1653)
HEYDON, Sir JOHN (d. 1653), military commander and mathematician, was the second son of Sir Christopher Heydon [q. v.] According to Wood, he was a distinguished soldier, and also an eminent scholar, being especially skilled in mathematics. In 1613 he was keeper of the stores in Sandown Castle, Deal, Kent. He was knighted in August 1620. In 1627 he was appointed lieutenant of the ordnance in the place of his brother Sir William, who was killed in the Isle of Rhé. Between 1627 and 1643 he was actively occupied in furnishing men, provisions, arms, guns, and ammunition for the service of the king (Cal. State Papers, Dom. 1627–43). When Charles I raised his standard at Nottingham 22 Aug. 1642, Heydon was in charge of cannon and ammunition at York. He soon joined the king, and accompanied the royalist army from Shrewsbury towards London in October 1642 (Clarendon, Hist. ed. Macray, ii. 293, 346). He acted as lieutenant-general of the ordnance with Charles's forces, and joined his privy council. He was made D.C.L. at Oxford on 20 Dec. 1642. Heydon suffered much for the king's cause. His goods were sequestrated, and there is an inventory of them in the British Museum, entitled ‘Inventarye of part of the Goods and Chattells of Sr John Hayden, knight, taken the 28 of Julye 1643,’ and also of ‘the goodes of Edward Stevens, seruant of Sir John Hayden, knight’ (Add. MS. 28191 d). Heydon died on 16 Oct. 1653.
[Wood's Fasti (Bliss), ii. 43; Blomefield's Topogr. Hist. of Norfolk, vi. 510; Anecdotes and Traditions, ed. Thoms (Camd. Soc.), pp. 23, 69.]