David Cameron has become the 15th former prime minister to serve in a later government led by someone else.
In a move which raised eyebrows across Westminster, Mr Cameron was seen in Downing Street on Monday morning, and was later appointed as Foreign Secretary by Rishi Sunak.
According to a Government blog from November 2012, 14 ex-premiers have previously come back in a different government role since the 18th century.
Sir Alec Douglas-Home, who served for just under a year as prime minister after taking office in October 1963, was later appointed foreign secretary by Edward Heath.
He held the role from 1970 until 1974 and is the last former PM to return to government under a different leader.
In earlier years, Arthur Balfour, who served as prime minister from 1902 until 1905, came back to government in the roles of the first lord of the admiralty in the wartime coalition, and then foreign secretary under David Lloyd George.
During the Second World War, Neville Chamberlain, who was succeeded by Sir Winston Churchill, went on to serve as lord president of the council in his Cabinet.
