David Cameron became the latest former British Prime Minister to serve in a government led by another PM this week.
There is no fixed role for former British Prime Ministers once they leave office, and many have remained as Members of Parliament or returned to serve in governments led by others.
This week, David Cameron was appointed Secretary of State for Foreign, Commonwealth and Development Affairs, making him the latest former Prime Minister to return to Cabinet under a different Prime Minister.
He served as Prime Minister from 2010 to 2016, leading Britain's first coalition government in nearly 70 years before forming the first majority Conservative government in the UK for almost two decades.
Now, he becomes Foreign Secretary - making him the first former Prime Minister to serve in the position after Sir Alec Douglas-Home, who took up the role from 1970-1974.
Here are some of the past Prime Ministers who returned to Cabinet after their premiership.
See David Cameron's first Cabinet meeting as Foreign Secretary with Prime Minister Rishi Sunak here.
Alec Douglas-Home
After his four-seat defeat to Harold Wilson at the 1964 general election, Douglas-Home returned to join Edward Heath's Cabinet as Foreign Secretary in 1970.
He was an unexpected Prime Minister and did not originally seek the position before being elected in 1963. He served for 363 days, and his government is remembered for overseeing the abolition of resale price maintenance.
Neville Chamberlain
Prime Minister Neville Chamberlain stood down as Prime Minister after coming under attack from all political sides after the failure of the British efforts to liberate Norway.
Following his resignation in May 1940, Chamberlain remained leader of the Conservative Party and acted briefly as Lord President of the Council, with ministerial responsibility for the Privy Council Office.
The Privy Council advises on the exercise of prerogative business and certain functions assigned to The King and the Council by Acts of Parliament.
Soon after standing down as Prime Minister, he was struck down with bowel cancer, forcing him to resign from Winston Churchill's coalition government and as leader of the party. He died shortly after his resignation.
Arthur Balfour
Arthur Balfour was Prime Minister for three years before defeats in the Commons and in by-elections led to his resignation in December 1905.
He continued to lead his party until 1911 and would go on to serve as a Cabinet Minister for eleven years during and after the First World War.
In 1915 he became First Lord of the Admiralty - the government's most senior advisor of naval affairs - in the wartime coalition. He became Foreign Secretary in David Lloyd George's coalition in 1916, and for the greater part of the 1920s he was Lord President of the Council in Stanley Baldwin's government.
Other Prime Ministers who returned to serve in government include Lord John Russell, Viscount Goderich and the Duke of Wellington, who after two brief terms as Prime Minister served as a minister in Robert Peel's government.
Former Prime Ministers who have returned to government:
- David Cameron.
Premiership: 2010 to 2016
Role: Foreign Secretary
- Alec Douglas-Home
Premiership: 1963 to 1964
Role: Foreign Secretary
- Neville Chamberlain
Premiership: 1937 to 1940
Role: Lord President of the Council
- James Ramsay Macdonald
Premiership: 1924 to 1924, 1929 to 1935
Role: Lord President of the Council
- Stanley Baldwin
Premiership: 1923 to 1924, 1924 to 1929, 1935 to 1937
Role: Lord President of the Council
- Arthur Balfour
Premiership: 1902 to 1905
Role: First Lord of the Admiralty, Foreign Secretary, Lord President of the Council
- John Russell
Premiership: 1846 to 1852, 1865 to 1866
Role: Foreign Secretary
- Arthur Wellesley
Premiership: 1828 to 1830, 1834 to 1834
Role: Foreign Secretary, Leader of the House of Lords
- Frederick Robinson
Premiership: 1827 to 1828
Role: Lord Privy Seal, President of the Board of Trade, President of the India Board
- Henry Addington
Premiership: 1908 to 1916
Role: Home Secretary
- William Cavendish-Bentinck
Premiership: 1783 to 1783, 1807 to 1809
Role: Home Secretary
- Frederick North
Premiership: 1770 to 1782
Role: Home Secretary
- Augustus FitzRoy
Premiership: 1768 to 1770
Role: Lord Privy Seal
- William Cavendish
Premiership: 1756 to 1757
Role: Lord Chamberlain
- Thomas Pelham-Holles
Premiership: 1754 to 1756, 1757 to 1762
Role: Lord Privy Seal
Click here to find out more about the latest ministerial appointments