in 1961 Harold Wilson — became Baron Wilson of Rievaulx in 1983 (life peer) Harold Macmillan — became the 1st Earl of Stockton in 1984 James Callaghan — became Baron Callaghan of Cardiff in 1987 (life peer) Margaret Thatcher — became Baroness Thatcher in 1992 (life peer) In contrast, 19 prime ministers preceding the current (Rishi Sunak) have never become members of the House of Lords, including his seven immediate predecessors. Henry Pelham (served 1743 to his death in 1754) was the first to be a lifelong "Commoner". (The convention of prime ministers leading from the House of Commons only became established in the 20th century.) Holders of Irish peerages (with the exception of 28 Irish representative peers allowed after 1801, who were elected from among their peers) legally did not sit in the House of Lords in the Parliaments of Great Britain and the United Kingdom, but were allowed to sit in the House of Commons. Lord Palmerston was the only Irish peer to serve as prime minister, thus leading from the House of Commons. Service in House of Commons The shortest period between entering Parliament and being appointed prime minister was achieved by William Pitt the Younger who became prime minister two years after first becoming an MP. The longest period of service as an MP before becoming prime minister was 47 years for Lord Palmerston. The oldest debut of a future prime minister as MP was by Neville Chamberlain who was elected, aged 49 years 261 days, at general election in 1918. The youngest at first election was Lord Euston (later the Duke of Grafton), who was elected at by election on 10 December 1756 aged 21 years and 73 days. He also had the shortest period as an MP enjoyed by a prime minister, nearly five months, representing two successive seats (the first of which he only held for 11 days before being elected for his second) until going to the House of Lords when he succeeded his father as the 3rd Duke of Grafton on 6 May 1757, eleven years before his term of office began. Winston Churchill served the longest as MP, for a total of 63 years and 360 days, for five successive seats, between 1 October 1900 and retirement on 25 September 1964, excluding two intervals out of parliament (in 1908 and in 1922–1924). He retired as Father of the House. He