Shortest-serving prime ministers Where in the list will Boris Johnson finish?

By calling an early election on Oct 15, Boris Johnson runs the risk of going down in the history books as Britain’s shortest serving prime minister.

Should MPS agree to an early election, Mr Johnson will have been in Downing Street for just 82 days on polling day.

If he fails to win a majority and leaves No10, he will have fallen far short of the previous shortest tenure: 119 days served by George Canning between April and August 1827.

However, unlike Canning, who died of pneumonia, aged 57, Mr Johnson’s departure will have been of his own making.

Following that, should he survive beyond middecember, Mr Johnson will move past the 1st Viscount Goderich, who succeeded Canning but could not hold together his coalition of Tory and Whig MPS. Goderich served for just 144 days – the second shortest tenure –before resigning.

He later served in the Cabinets of two of his successors, Earl Grey and Sir Robert Peel.

He is followed in the league table by Andrew Bonar Law, who served 211 days between 1922 and 1923. Despite winning a clear majority in an election, Bonar Law was forced to resign due to throat cancer. He died five months later.

Other prime ministers who failed to reach one year in office include William Cavendish, 4th Duke of Devonshire, who took office in 1756 and served for 226 days; William Petty, 2nd Earl of Shelburne, who took office in 1782 for 266 days, and John Stuart, 3rd Earl of Bute, who served for 318 days in 1762.

To avoid becoming the shortest-serving prime minister in modern times, Mr Johnson will need to stay the course for a year. Should he do so, he will eclipse Alec Douglashome, who served for 364 days until Oct 16 1964.