Leonard Smelt (c1719-1800) was the son of William Smelt of Kirby-Fleetham in Yorkshire, who was briefly MP for Northallerton. He became a Captain in the Royal Engineers, and saw action at the Battle of Dettingen and against the Jacobite rebels in the north-east of England. In 1770 he was appointed sub-governor to the Prince of Wales and the Duke of York, sons of George III, on the recommendation of his friend Lord Holderness, the royal governor. He resigned his post after ten years and declined a pension, but remained friendly with the king and queen. He was an intimate friend of Fanny Burney, and a member of the Bluestocking circle. Such different characters as Mary Delany and Horace Walpole praised him highly. In 1744 he married Jane Campbell (d.1790), and they had two daughters, Ann and Dorothea. In 1792, following the death of his wife, he retired to his estate at Langton Hall in Yorkshire, where Elizabeth Montagu had visited him in 1778 and 1781 during her journeys to Northumberland. (The house passed to Nathaniel Cholmley, husband of his daughter Anne, and survives today as a school.) Smelt was distantly related to Elizabeth Montagu: his great-great-grandfather Matthew Smelt (1594-1652) was the brother of her great-great-grandmother Frances Smelt (1604-1687) who married Thomas Robinson (1593-1643).