This post was contributed by Eloise Ellis, Senior Lecturer in Law.

The last few years have been a time of significant flux in the British constitutional structure – we left the European Union (Brexit), campaigns for Scottish independence continued to rumble and we experienced a global pandemic – but perhaps none more so than 2022. In addition to an unprecedented number of ministerial resignations, in this single calendar year we have had three different Prime Ministers (until 6th September, Boris Johnson, then from 6th September to 25th October, Liz Truss, and finally from 25th October, Rishi Sunak). The average modern-day British Prime Minister stays in post for approximately five years, thus recent events have drawn attention to our system of representative government, highlighted the operation of the Westminster model and the pivotal role played by constitutional convention, all of which perhaps is often misunderstood.

As voters in the United Kingdom, we do not elect our Prime Ministers directly or even indirectly, rather we cast our vote for our local representative, our constituency Member of Parliament (MP). It is the Monarch, through prerogative powers, who appoints the Prime Minister, however, by firmly established constitutional convention this will be the person who can ‘command the confidence of the House of Commons’ which in practice is understood to mean the leader of the largest political party in the Commons. The Prime Minister is directly responsible to Parliament rather than to the electorate. It is also constitutional convention which dictates that the Prime Minister will be an MP rather than a member of the House of Lords.

It is not uncommon for a change of Prime Minister to happen during the life of a Parliament and constitutionally there is no requirement for a general election for this to happen. It is, however, unusual to have such frequent changes. Liz Truss was the Head of Government for a mere 50 days – the shortest term of any British Prime Minister. She was also the last Prime Minister to be appointed by the late HM Queen Elizabeth II, whose long reign was served by 15 Prime Ministers. Truss’ successor, Rishi Sunak, the incumbent, is the first Prime Minister to be appointed by a King in over 70 years, the youngest PM in modern history at 42, and the first ever British-Asian Prime Minister. Events this year have raised public awareness of our constitutional system and the political party machinery behind the choice of leader. Different political parties have different procedures by which their leaders are chosen. For the Conservative party (which has provided the last five Prime Ministers, including the current incumbent, that is, Cameron, May, Johnson, Truss and Sunak), the process (as amended in 1998) involves both MPs and the party membership outside the precincts of Westminster. In the first stage, MPs interested in standing must achieve the support of a set number of MPs in order to be a candidate, those standing are then reduced by elimination in successive ballots, in which the sitting Conservative MPs vote, until only two candidates remain. In the second stage, the party membership is balloted to choose between these two. Recent events have been particularly interesting as in September 2022 the two candidates who were put out to the membership to vote were Liz Truss (who got the support of 57.4% of the votes) and Rishi Sunak (who received 38.3%), both of whom have now served as Prime Minister. In October, under revised rules which meant that MPs interested in standing must achieve the support of at least 100 MPs in order to be a candidate, Sunak was the only candidate (Penny Mordant having withdrawn from the contest) and so was (s)elected unopposed. One novel and particularly controversial aspect was the possibility that Boris Johnson would stand again to be chosen as leader and thus return to No. 10 Downing Street. The party’s rules forbid the departing PM from standing in the contest to appoint their immediate successor, but they are not prevented from entering any subsequent ballots.
It appears that this period of turbulence is over and Government is now stabilising, Sunak has pledged to lead a Government which will have ‘integrity, professionalism and accountability at every level’. An important aim given the circumstances which brought about the ousting of Johnson as Prime Minister, following repeated scandals including ‘partygate’ which ultimately led to the loss of support of his party and culminated in a swathe of ministerial resignations over two days in July .
In this year’s Rothschild Foster Human Rights Lecture Professor Jeffrey Jowell posed the question whether a change of prime minister should require support only from their party or from the wider electorate. This is an idea you might like to explore, noting that similar criticisms have been voiced in the past, including when Gordon Brown succeeded Tony Blair in 2007 as the last Labour Prime Minister during the last Parliament under a Labour Government.
For further detail on the process of appointing a Prime Minister you might like to read House of Commons Library Note ‘How is a Prime Minister appointed?’.
how is this constitutional convention important