Harcourt, Simon (1714–77), 1st Earl Harcourt of Stanton Harcourt, diplomat, and lord lieutenant of Ireland (1772–6), was the only son of Simon Harcourt (1684–1720), barrister and Westminster MP, and his first wife, Elizabeth Harcourt (née Evelyn). Educated at Westminster School, he succeeded to the titles and estates of his grandfather, Viscount Harcourt, in 1727. A lord of the bedchamber (1735–51), he raised his own regiment during the Jacobite rising (1745) and became a general in the army (1772). On 1 December 1749 he was created Viscount Nuneham of Nuneham Courtney and Earl Harcourt of Stanton Harcourt. In a successful diplomatic career he escorted Princess Charlotte, the future queen of England, from Mecklenburg in 1761 and was her lord chamberlain (1763–8); he was then ambassador to Paris (1768–72).
On 29 October 1772 he was appointed lord lieutenant of Ireland; he was sworn in on 30 November, John Blaquiere (qv) accompanying him as chief secretary. His tact and courtesy won many admirers, and was in sharp contrast to the administration of Lord Townshend (qv) during its final months. In 1773 Harcourt’s proposal to raise revenue through a tax on absentee landlords caused much consternation and the government was obliged to remain neutral on the issue. The prime minister, Lord North, was dissuaded from addressing Irish affairs by the reaction to the tax, and Harcourt became vulnerable in London to the intrigues of Lord George Germain, secretary of state for the colonies, who campaigned for his dismissal and replacement by John Hobart, 2nd earl of Buckinghamshire (qv), even complaining to George III about Harcourt's ‘presumption’.
One notable success of Harcourt's administration was to persuade Henry Flood (qv) to accept office as vice-treasurer, and he also made John Hely-Hutchinson (qv) provost of TCD. When trouble with the colonies broke out in 1776, he secured parliamentary support for the conflict and sent 4,000 troops to America. In a determined assertion of the government's control of the patronage system he created in a single day eighteen peers to ensure new and dependable supporters in the house of lords. Succumbing to the pressure on his position after a dispute with the commander-in-chief over the latter's powers, he resigned in December 1776 and returned to England.
He married 16 October 1735 Rebecca, daughter and heir of Charles Samborne, and his wife, Mary Samborne (née Moyer); they had two sons and two daughters. He was succeeded by his sons George Simon, and then William, as 2nd and 3rd earls Harcourt. He died 16 September 1777 by drowning while attempting to rescue his favourite dog, and was buried at Stanton Harcourt.