Daily Junction.mobi portalPolitics · July 11, 2026 · Sarah Mitchell · 4 min
No British government is sworn in by winning an election; it forms when someone can command Commons confidence, guided by incumbency rights, caretaker conventions and the arithmetic of 2010 and 2017.
Nobody hands a British prime minister a certificate of victory. There is no inauguration, no formal declaration that one party has won, and no statute setting out what happens when none of them does. A government exists when, and only when, it can command the confidence of the House of Commons — and everything else, from who gets first go at forming one to who runs the country during the haggling, is done by convention, most of it written down only as recently as the 2011 Cabinet Manual.
The arithmetic starts simply and then gets stranger. The Commons has 650 seats, so the winning line is nominally 326. In practice it sits lower. Sinn Féin MPs do not take their seats, the Speaker and three deputies do not vote in ordinary divisions, and so a working majority in recent parliaments has needed something closer to 320 to 322 votes. A party can therefore be short of 326 and still govern comfortably, or hit 326 on paper and find its effective cushion thinner than it looks once tellers, illness and by-election losses are counted.
When no party reaches that line, the first convention to bite is incumbency. The sitting Prime Minister remains in office and is entitled to remain until it is clear either that they can command confidence or that someone else can. This is not squatting; it is a constitutional duty, because the country must have a government at every moment and the monarch must never be left to arbitrate between rival claimants. In May 2010 Gordon Brown stayed in Downing Street for five days after finishing second in seats and votes, and the tabloids that accused him of clinging on had the convention exactly backwards. He was obliged to stay until David Cameron and Nick Clegg had a deal capable of surviving a confidence vote.
While the talks run, the caretaker principle governs. A government in this position carries on essential business but defers significant appointments, contracts and policy departures that would bind its successor, on the same logic as the pre-election purdah period. The civil service, meanwhile, does something unusual: with the Prime Minister's authorisation, as Brown gave the Cabinet Secretary Gus O'Donnell in 2010, officials support negotiations between other parties, costing policy packages for combinations of politicians who may be about to eject their current employer.
The 2010 result — Conservatives 306, Labour 258, Liberal Democrats 57 — showed why the maths, not the largest-party label, decides the shape of the outcome. A Labour–Liberal Democrat pact would have reached only 315, short of a majority even with nationalist support, and each extra partner raises the price and lowers the stability. Conservatives plus Liberal Democrats made 363, a genuine cushion, and that surplus is why Britain got its first full peacetime coalition since the 1930s rather than a minority administration: the numbers made a formal, programme-based government worth the Liberal Democrats' risk. The Coalition Agreement, negotiated in five days, ran to a detailed programme for government, with ministerial posts distributed roughly in proportion to seats contributed.
The 2017 result — Conservatives 317, Labour 262, DUP 10 — produced the other model. Theresa May stayed in office, again by incumbency convention, and reached not a coalition but a confidence-and-supply agreement: the DUP promised its ten votes on confidence motions, Budgets and specified priorities, in exchange for around £1 billion of additional spending in Northern Ireland, while taking no ministerial jobs and reserving its position on everything else. That is the cheaper, looser instrument a small partner prefers when its votes alone tip the balance, and it left May's government to lose ordinary divisions repeatedly without ever quite losing confidence.
Whatever is agreed in private, the proof comes on the floor of the House. The traditional moment is the vote on the King's Speech, the new government's legislative programme, usually held within weeks of the election; a government that cannot carry it has failed the confidence test at the first attempt, something that last happened to Stanley Baldwin in January 1924, ushering in the first Labour government. Since the repeal of the Fixed-term Parliaments Act in 2022, losing a designated confidence vote points once more towards resignation or a request for dissolution, restoring the older, starker logic.
That is the whole machine. No referee blows a whistle. Seats are counted, conventions allocate the first move, the civil service keeps the lights on and the spreadsheets honest, and the Commons delivers the only verdict that matters — which is why the government of the United Kingdom is never elected, only sustained.
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