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KEIR STARMER announced his resignation outside Number 10 on June 22nd, less than two years after winning one of the largest parliamentary majorities in modern British history. He resigned because roughly 110 of his own MPs had publicly demanded he set a date for leaving, four ministers had quit in protest and a rival, Andy Burnham, had just engineered his way back into Parliament specifically to challenge him. The mechanism Burnham used was almost comically blunt: a sitting Labour MP resigned his safe seat at Makerfield purely to create a vacancy Burnham could win, the first time anyone has manufactured a by-election this way since 1965. Within four days of that by-election victory, the prime minister of the United Kingdom was gone.
What makes this remarkable is how unremarkable it has become. David Cameron resigned in 2016 after losing the Brexit referendum. Theresa May resigned in 2019 after Parliament rejected her withdrawal deal three times. Boris Johnson resigned in 2022 under the weight of Partygate and a cabinet revolt. Liz Truss lasted 49 days before her own mini-budget triggered a bond-market panic that her party could not survive politically. Rishi Sunak called an election he lost. Starmer is now the latest entry on a list that has turned Downing Street into something closer to a managed rotation than a fixed five-year office.
The proximate cause each time looks different: Brexit, a leadership coup, a budget crisis, an election defeat, a backbench rebellion. The underlying trigger is identical, and it is worth being accurate about what it actually is.
In Britain’s parliamentary system, the prime minister is not directly elected by the public at all. The job belongs to whoever can command the confidence of the House of Commons, which in practice means whoever leads the largest party, which in practice means whoever that party’s own MPs currently prefer. Voters choose a parliament once every few years. Between those elections, an incumbent prime minister’s job security depends entirely on some 400 backbenchers and a leadership rulebook, not on any public vote at all. That has always been true, technically. What has changed is how fast and how casually that internal mechanism now gets triggered.
Part of the answer is mathematical. Starmer’s 2024 landslide delivered Labour about 63% of the seats in the Commons on roughly 34% of the national vote, the most lopsided majority-to-vote-share ratio in modern British electoral history. A majority built that slim is, paradoxically, less stable than it looks, because hundreds of Labour MPs now sit in seats they know they could lose on a relatively small swing, particularly with Reform UK surging on one flank and the Greens picking up disaffected voters on the other. MPs who fear for their own seats are quicker to conclude that removing their leader is less risky than waiting for him to recover. Margaret Thatcher’s parliamentary party removed her in 1990 only after eleven years and considerable institutional hesitation. It took Starmer’s party roughly eleven months of grumbling and one bad set of local election results, in which Labour lost nearly 1,500 council seats in May, to reach the same conclusion this time.
There is also a simple precedent effect. Once a governing party has shown it can remove a sitting prime minister mid-term without an election, every subsequent party finds the maneuver a little easier to contemplate, and every subsequent leader knows their own MPs have watched it happen and absorbed the lesson. Labour spent 2022 loudly attacking the Conservatives for swapping Boris Johnson and then Liz Truss without consulting voters, insisting any change of prime minister demanded a fresh democratic mandate. That argument did not survive Labour’s own turn in office. The mechanism has become bipartisan, almost reflexive, and entirely unconnected to what voters actually decided at the last general election.
None of this required a single change to Britain’s constitution. The rules that let Starmer’s party discard him are the same rules that have governed Westminster for generations. What has changed is the patience of the people using them, and patience, unlike a written constitution, can run out a great deal faster than anyone expects. ■
