With the resignation of Liz Truss as Prime Minister of the United Kingdom after just over a month in power, you may be wondering who served as UK Prime Minister for the least amount of time. The United Kingdom has had 56 Prime Ministers since Robert Walpole, who is considered the de facto first Prime Minister, and the time those people held office varies a lot; Robert Walpole served for over 20 years, and the longest time in office in modern politics was Margaret Thatcher at 11 years and 208 days. Check out the list below to find out about the 5 shortest serving UK Prime Ministers in history.
5. William Cavendish, 4th Duke of Devonshire (226 Days as Prime Minister, 16 November 1756 – 29 June 1757)

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William Cavendish, 4th Duke of Devonshire was appointed as the First Lord of the Treasury on the 16th of November 1756 and led the government for 226 days until he resigned on the 29th of June 1757. It is generally believed that Cavendish’s position as Prime Minister was only ever going to be temporary until the previous PM, Thomas Pelham-Holles, 1st Duke of Newcastle, who had fallen out with prominent politician William Pitt the Elder, returned to the position after reconciling their differences. This is exactly what happened with Cavendish sitting in the new Pitt–Newcastle ministry as Lord Chamberlain until his resignation from this position in 1762.
4. Andrew Bonar Law (209 Days as Prime Minister, 23 October 1922 – 20 May 1923)

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Andrew Bonar Law was a prominent politician who served as the Leader of the Conservative Party shortly after the First World War. He became Prime Minister of the United Kingdom on the 23rd of October 1922, following the resignation of David Lloyd George. Bonar Law’s time in office lasted just 210 days, resigning as Prime Minister on May 20th, 1923, due to being diagnosed with terminal throat cancer. Bonar Law died as a result of the disease 6 months later.
3. Frederick John Robinson, 1st Viscount Goderich (144 Days as Prime Minister, 31 August 1827 – 21 January 1828)

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Frederick John Robinson, 1st Earl of Ripon, became Prime Minister of the United Kingdom following the death of George Canning on August 8th, 1827, while he was in office. Robinson led the Tory and Whig coalition for 144 days before being pressured to resign on January 21st, 1828, by King George IV and was asked to arrange his own replacement. He remained as a senior member of the Tory and Conservative party for many years after his resignation, holding multiple ministerial roles such as Secretary of State for War and the Colonies and President of the Board of Trade.
2. George Canning (119 Days as Prime Minister, 12 April 1827 – 8 August 1827)

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Until recently, George Canning held the record for the shortest premiership in British history with 119 days as Prime Minister. Taking the position on the 12 of April 1827 after the previous Prime Minister, Robert Jenkinson, 2nd Earl of Liverpool, suffered a stroke in office, Canning lasted less than 5 months before he caught pneumonia and died at Chiswick House on the 8th of August 1827.
1. Liz Truss (50 Days as Prime Minister, 6 September 2022 – 26 October 2022)

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Earning the title of “shortest serving Prime Minister in British History” on October 20th, 2022, when she resigned after just over a month in power. Serving as Prime Minister for just 45 days before announcing her resignation and being replaced by Rishi Sunak in a conservative leadership contest in the next week, Liz Truss beats out the former holder of the title George Canning (who died in office) by 69 days.
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