Why Britain devours its prime ministers

For much of the post-war era, Britain was known for prime ministers who lasted. Once a leader reached Downing Street, they were expected to stay there. The dominance of two established parties, relatively disciplined parliamentary blocs and a first-past-the-post electoral system that often turned votes into workable Commons majorities all helped give prime ministers a stable base. Margaret Thatcher and Tony Blair both got something that now seems almost unimaginable: a decade in power. But British prime ministers are now coming and going in quick succession. The country is on course for its seventh prime minister in a decade. Theresa May and Boris Johnson each lasted just over three years. Liz Truss managed only 49 days. Keir Starmer was supposed to be different: he entered Downing Street after Labour won a landslide majority in 2024. Yet he, too, is now leaving after barely two years. Why has Britain’s famed stability given way so quickly to political chaos? There are several obvious explanations, but none is enough on its own. Has social media helped harden political divisions? Almost certainly. But Britain is hardly the only country with the internet. Has Brexit made the country harder to govern? Yes. It cut across party lines, deepened political identities and left prime ministers managing not just policy disputes but rival ideas of what the country should be. Yet, as academics have pointed out, Brexit did not create Britain’s instability out of nowhere. …