The secretary of state for defence is a relatively modern cabinet position having only come into existence in 1964. It evolved from the position of minister of defence, which in turn came from the minister for co-ordination of defence.
7th - Michael Heseltine (1983 – 1986)
The seventh longest-serving defence secretary was Michael Heseltine, Thatcher’s long-time political rival, who held the role between 1982 and 1986. He later served as deputy prime minister under John Major during his final years in office. Heseltine was defence secretary for three whole years.
6th - Malcolm Rifkind (1992 - 1995)
Rifkind was John Major’s defence secretary for three years and three months until he was promoted to the position of foreign secretary in 1995. He lost his seat at the 1997 general election to in the great Labour landslide, but returned to the Commons in 2005 before retiring from formal politics in 2015.
5th - Michael Fallon (2014 – 2017)
Michael Fallon resigned from the country’s top defence job on Wednesday and was succeeded by former Chief Whip Gavin Williamson the next day. He was first appointed to the role in 2014, and lasted three years and four months in the job. How long will his successor last?
4th - George Younger (1986 – 1989)
Younger served as Margaret Thatcher’s secretary of state for Scotland for most of Britain's first female prime minister's premiership. He served in that role from 1979, but in 1986 he was moved to defence, a position he held for a further three years and six months. Younger passed away in 2003.
3rd - Peter Carrington (1970 – 1974)
Carrington served as defence secretary for the first three years and seven months of Edward Heath’s short premiership. In January 1974, he was replaced by Ian Gilmour and given the energy portfolio.
2nd - Denis Healey (1964 – 1970)
The second longest-serving British defence secretary was Denis Healey, who served in the role during the first Wilson administration. He lasted five years and eight months in the job. Four years later, after Heath’s spell in power, Healey was made chancellor of the exchequer when Labour’s Wilson became PM for a second time. Then back in opposition, Healey was made deputy leader of the Labour party under Michael Foot, but stepped down following the party’s historic election defeat in 1983.
1st - Geoff Hoon (1999 – 2005)
Hoon takes the top spot, having served as defence secretary for five years and nine months – just a little longer than Healey. This Labour MP served in a variety of government roles, starting with his position as a foreign minister under Tony Blair in 1999. Two months later he was made secretary of defence, a role he held for almost six years. Then, after the 2005 election he became the minister for Europe. He stepped down at the 2010 election and his seat is now held by Labour's Gloria De Piero.