Elliot, William (1766–1818), chief secretary for Ireland (1806-7) and MP, was born 12 March 1766 in Reigate, Surrey, only child of William Nassau Elliot, barrister, and Martha Elliot (née Meade). Although English-born, he was of Scottish descent and was educated first privately, and then at Aberdeen (1783–5) and Inner Temple (1783). He disliked the law, however, and influenced by his distant relative, Sir Gilbert Elliot, a prominent whig, decided upon a career in politics. After becoming friends with Richard Burke (1758–94), he met his father, Edmund Burke (qv), through him, and was a regular visitor at their Beaconsfield home. Elliot's intelligence and argumentative ability won him the friendship of both the elder Burke and Earl Fitzwilliam (qv). Opposed to the French revolution, he is believed to have become a proponent of catholic emancipation in 1795 after Burke wrote him a public letter, dated 26 May, on the Fitzwilliam affair.
Failing to secure a parliamentary seat in Britain, in 1796 he went to Ireland, as private secretary to the new chief secretary, Thomas Pelham (qv). He succeeded Edward Cooke (qv), as under-secretary for the military department (secretary-at-war), and became an MP in the Irish commons, representing St Canice, Co. Kilkenny, the government borough (1796–1800). In March 1798 he was recommended for the position of acting chief secretary after Pelham's illness, but his own poor health, which had given rise to the sobriquet ‘the Castle spectre’, forced him to decline. Viscount Castlereagh (qv) later succeeded Pelham, and established a firm and lasting friendship with Elliot.
During the long union negotiations, he was often employed by Lord Cornwallis (qv) on important missions. In October 1798 the viceroy sent him to London to counterbalance the anti-catholic arguments of the earl of Clare (qv), but he failed to prevent the prime minister, William Pitt, from deciding against emancipation. Elliot became disillusioned and tendered his resignation (November), but was persuaded to withdraw it after Castlereagh and Cornwallis assured him that emancipation was still possible. He visited England throughout 1799 and 1800, briefing ministers on the union.
After the union he became MP for Portarlington, Queen's Co. (1801–2), but was forced to vacate this seat because of his opposition to the new prime minister, Henry Addington, and was returned by Fitzwilliam for Peterborough (1802–18). He spoke well, but not often, in parliament. His main efforts were directed against France, but he also believed that those who voted for union had a special responsibility towards Ireland, and he feared that he might some day regret its passage. He voted in March 1804 for the inquiry into the rebellion of Robert Emmet (qv), and opposed William Pitt's second ministry later that year.
With the formation of a ministry by Lord Grenville (qv) in 1806, he was persuaded to return to office. He reluctantly accepted the post of chief secretary for Ireland on 28 March 1806, despite the continuing poor state of his health. His second period in Ireland was not a happy one, he received the new sobriquet of ‘Le revenant’, and had difficulties with the Irish elections and the catholic leaders. Nevertheless, he supported the grant to Maynooth College, and continued to be sympathetic to catholic relief. He resigned in April 1807 with the collapse of the ministry, and returned to England where he resumed opposition.
Voting for catholic relief consistently in the 1810s, he opposed parliamentary reform. After refusing office in February 1811, a month later he was the only English MP to support the speech of George Ponsonby (qv) on catholic relief. In 1817 he became ill and his attendance at parliament become more infrequent. In private he was quiet and serious, and Sir Gilbert Elliot joked that he was dead to enjoyment ‘like a wet blanket on a fire’. He died 26 October 1818 at Minto House, Wells, Co. Roxburgh, and was buried at Reigate cemetery. He did not marry.