6 August 2019updated 07 Jun 2021 4:19pm

Does Boris Johnson have to resign as Prime Minister if he loses a confidence vote?

LONDON, ENGLAND - JULY 24: New Prime Minister Boris Johnson arrives in 10 Downing Street on July 24, 2019 in London, England. Boris Johnson, MP for Uxbridge and South Ruislip, was elected leader of the Conservative and Unionist Party yesterday receiving 66 percent of the votes cast by the Party members. He will take the office of Prime Minister this afternoon. (Photo by Stefan Rousseau - WPA Pool/Getty Images)

If the government loses a confidence vote, does the prime minister have to resign?

The answer is complicated. There’s nothing written in British law that compels a prime minister to resign after an election defeat – technically, it’s the role of the monarch to remove a prime minister who can no longer command a majority in the House of Commons.

But a British monarch hasn’t used this power since 1834 – and hasn’t been personally involved in a change of government since 1894, when Queen Victoria opted to send for Archibald Rosebery, a Liberal peer on the party’s right, rather than William Harcourt, a Liberal MP on the party’s left. So, in practice, it’s convention that ensures that election results are upheld and our elected House of Commons chooses who governs our country.

When the election result has been a clear defeat – as with Jim Callaghan in 1979 and John Major in 1997 – prime ministers have resigned not because of the automatic force of law but because of the convention that they should do so. When the election result has been unclear – as with Ted Heath in 1974, Gordon Brown in 2010, and Theresa May in 2017 – the sitting prime minister has carried on in order to see if an alternative coalition, either to maintain their own government or to see if the creation of a new one can be found, though in the cases of both Heath and Brown they were ultimately forced out by arrangements between the other parties.

But what if a prime minister loses their majority not at an election but midway through the parliament, as Jim Callaghan (him again!) did on 31 March 1977, when Labour lost its overall majority after being defeated in a by-election in Birmingham Stechford?

Well, in 1977 the prime minister had three options. He could call a fresh general election in a bid to get a new parliamentary majority. He could tell the monarch that another member of parliament was able to command a majority in the House of Commons. Or he could seek to form a government through an alternative arrangement, as Callaghan did by striking a deal with the Liberal Party to provide the government with a majority.

But if historically a sitting prime minister has lost a confidence vote then it is, or at least was clear: they can either call an election (as Callaghan did in 1979) or recommend that the monarch calls on another politician to form a government.

So in 2019 it’s open and shut, right? If Boris Johnson loses a confidence vote then he has two options: he can tell the monarch to send for another prime minister, or he can seek an election… but that’s where it gets messy.

Why? Because in 2010, parliament passed the Fixed-term Parliaments Act into law, which gives control over the date of the next election not to the executive but to the legislature. Now, if the government loses a confidence vote there is a 14-day period in which it has the power to seek a fresh confidence vote, and if it can’t get one, then there is an election.

But what is not wholly clear is whether that 14-day period is a free-for-all, in which, say, Jeremy Corbyn can do a deal with Nicola Sturgeon, Jo Swinson and Tory dissidents to form a cross-party government to seek an Article 50 extension for a fresh government, or one in which only the sitting prime minister can seek to extend their time in office.

Because having been no-confidenced, the government retains its power at the start of the 14 days to ask parliament for dissolution under the Fixed-term Parliaments Act by seeking a two-thirds majority. But equally, if the prime minister has fallen out with one set of coalition partners (in our case the DUP), then they might then seek to form a confidence-and-supply agreement with another group (perhaps the small but significant group of pro-Brexit independent backbenchers).

In practice, what I think will happen when push comes to shove, is that parliament will, effectively, establish how the Fixed-term Parliaments Act and government formation works in practice when the moment arises. The Downing Street/Cummings argument – or rather, its hope – is that in practice the government still retains the ability to decide how it responds, rather than having the choice made for it.