Liz Truss becomes the 16th prime minister to have served the UK during the reign of Queen Elizabeth II. The Conservative Party leader officially became the country's prime minister after meeting the monarch in what is known as the 'kissing hands' ceremony.
It is ceremony dating back to the time when the monarch had the power to form and dissolve parliament, it marks the official start of a prime minister's time in office – and is purely ceremonial, as Queen Elizabeth has never refused the formal request.
We have sourced photographs from the time a 25-year-old Elizabeth met Winston Churchill soon after becoming Queen of the United Kingdom through to her most recent encounter, when she broke with tradition by receiving Truss at her summer residence of Balmoral because she was not well enough to travel to Buckingham Palace, her London home.
Winston Churchill 1951-1955
Churchill adored Queen Elizabeth, pictured here with Prince Charles and Princess Anne in 1953. /Central Press/Getty Images
Anthony Eden 1955-1957
Conservative PM Eden bows to the Queen at the Banquet Hall in London, May 1956. /Keystone-France/Gamma-Keystone via Getty
Harold Macmillan 1957-1963
The Queen visits conversions of old houses near Oxford Circus with Conservative housing minister Macmillan, a few years before he became PM. /CFP
Alec Douglas-Home 1963-1964
Douglas-Home was Conservative PM for slightly less than a year. /Creative Commons
Harold Wilson 1964-1970
Pictured here with the Queen in 1969, Wilson had in 1964 become Labour's first PM in 13 years. /Fox Photos/Hulton Archive/Getty Images
Edward Heath 1970-1974
Conservative leader 'Ted' Heath and the Queen welcome U.S. President Richard Nixon in 1970. /CFP
Harold Wilson 1974-1976
Labour regained power in 1974, but Wilson is pictured meeting the Queen after resigning in 1976. /Wesley/Keystone/Getty Images
James Callaghan 1976-1979
Labour leader Callaghan is pictured arriving at Windsor Castle for lunch in December 1977. /David Ashdown/Keystone/Getty Images
Margaret Thatcher 1979-1990
The longest-serving PM under Queen Elizabeth II, Thatcher is pictured with the monarch at a 1979 Commonwealth ball in Zambia. /CFP
John Major 1990-1997
The Queen presents former Conservative PM Major with the Companion of Honour in 1999. /CFP
Tony Blair 1997-2007
Blair, Labour's first PM in 18 years, is pictured with the Queen at Buckingham Palace in 2002. /Anwar Hussein/Getty Images
Gordon Brown 2007-2010
The Queen Labour PM Brown as she officially opens St. Pancras International Station in 2007. /Anwar Hussein Collection/ROTA/WireImage
David Cameron 2010-2016
The Queen at Downing Street after lunch with Conservative PM Cameron and his wife Samantha in 2011. /Stefan Rosseau/WPA Pool/Getty Images
Theresa May 2016-2019
Conservative leader May, the UK's second female PM, sits with the Queen at Buckingham Palace in 2018. /Yui Mok-WPA Pool/Getty Images
Boris Johnson 2019-2022
Having been voted in by the Conservative party members, Johnson is received by the Queen at Buckingham Palace and appointed PM in, 2019. /CFP
Liz Truss 2022
The Queen invites Conservative Truss to become PM at Balmoral Castle, Scotland, on September 6, 2022. /Jane Barlow/Pool/Reuters