Boris Johnson will have clocked up just over 500 days as Prime Minister by the time he celebrates the first anniversary of his general election victory on December 12.
But he has already spent longer in Downing Street than two of his 20th-century predecessors.
Andrew Bonar Law lasted just 211 days in the top job in 1922-23 while Alec Douglas-Home managed 364 days in 1963-64.
Mr Johnson has already outrun both of these former Conservative PMs and will hit 507 days on December 12.
Next year he is set to overtake two more of his modern-day predecessors: Anthony Eden, who notched up 644 days as Tory prime minister from 1955 to 1957; and Henry Campbell-Bannerman, who was Liberal PM for 852 days from 1905 to 1908.
He will have to stay in Downing Street even longer before outlasting more recent PMs, however.
Mr Johnson would pass Gordon Brown (1,049 days) and Theresa May (1,106 days) by the end of 2022.
If he makes it all the way to end of 2025 – winning another general election in the process – he will have overtaken David Cameron (2,255 days).