Records of Prime Ministers of the United Kingdom

Records of Prime Ministers of Great Britain and Prime Ministers of the United Kingdom from 1801 to the present.

The Prime Minister with the longest single term was Sir Robert Walpole, lasting 20 years and 314 days from 4 April 1721 until 11 February 1742. This is also longer than the accumulated terms of any other Prime Minister.

The shortest period in office is more confused, depending on the criteria. The shortest ever period was only two days, a record held by Lord Bath, from 10 February to 12 February 1746, who was asked to form a government but was unable to find more than one person who would agree to serve in his cabinet. A satirist of the time wrote: "the minister to the astonishment of all wise men never transacted one rash thing; and, what is more marvellous, left as much money in the Treasury as he found in it." James Waldegrave, 2nd Earl Waldegrave was a prime minister for four days, from 8 June to 12 June 1757. However, since neither of these Earls actually formed an effective government, there are other contenders for the record of shortest term of office among those who actually governed the country.

In November 1834, the Duke of Wellington declined to become Prime Minister in favour of Sir Robert Peel but formed a "caretaker" administration for 25 days (17 November 1834 – 9 December 1834) while Peel returned from Europe. However, as a caretaker administration this might not necessarily be considered a term of office in its own right.

Therefore, of those with clear and effective terms, the Prime Minister with the shortest single one was Lord Rockingham, whose second term lasted 96 days from 27 March 1782 until his death on 1 July 1782. However, combined with his first term (13 July 1765 – 30 July 1766) his total time in office was 1 year and 113 days, which exceeds the total periods of several other Prime Ministers. (The Duke of Wellington had also served as Prime Minister between 1828 and 1830.)

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