Ten years to the day after Britons voted 52 percent to 48 percent to leave the European Union, the United Kingdom is preparing to install its seventh prime minister of the decade. Keir Starmer's resignation outside 10 Downing Street on Monday, the eve of the anniversary, closed a stretch in which no occupant has lasted longer than three years and one lasted 49 days.

The pairing of date and departure has crystallized a verdict the country largely resisted for most of the decade. A YouGov survey this month found that 30 percent of Britons now believe leaving the bloc was the right choice, down from 64 percent on referendum day, and 57 percent think it was wrong. Six in 10 judge Brexit an outright failure.

The economic ledger

Stanford economist Nicholas Bloom estimates that by 2025 Brexit had reduced U.K. gross domestic product by 6 to 8 percent, in line with a Bank of England analysis cited by Al Jazeera that puts the shortfall at 6 percent. Bloom attributed the drag to "elevated uncertainty, reduced demand, diverted management time, and increased misallocation of resources from a protracted Brexit process."

The pound has spent 98 percent of post-referendum trading sessions below €1.20, according to Convera, averaging €1.16 against the euro since June 2016, down from €1.27 in the preceding decade. The EU still accounts for 41 percent of U.K. exports and 50 percent of imports, or more than €800 billion combined.

London's equity benchmarks tell a split story. The multinational FTSE 100 has outperformed the domestically oriented FTSE 250, with neither keeping pace with U.S. indexes. "The UK stock market is little changed to ten years ago," Mark Preskett, a portfolio manager at Morningstar, told CNBC. Chris Smith of Jupiter cited sterling weakness, FX-led inflation and a higher cost of capital as creating "a more challenging backdrop for UK-focused businesses."

The political ledger

Net migration, the metric the Vote Leave campaign promised to bring down, climbed from 335,000 in 2016 to 944,000 in 2023 before falling to 171,000 last year, as collapsing EU arrivals were more than offset by non-EU work and student visas. The two-party system that produced Tony Blair and Gordon Brown has splintered, with Nigel Farage's hard-right Reform UK leading opinion polls and the Greens drawing voters on the left.

The academic Chris Grey told NPR that "the subterranean trace of Brexit" still runs through Britain's unruly politics. International politics professor Scott Lucas, speaking to NBC News, was blunter: "Why is the economy so unstable today? Brexit. We might as well say the quiet part out loud."

The other side

The defense now comes mostly from those who built the project. Guto Hari, communications director for former Prime Minister Boris Johnson, told NBC News that voters had been changed by Brexit as much as the country had: "Whereas we used to be more cool and rational, the electorate is more fickle, it wants more instant gratification, and it gets frustrated more quickly." Leave campaigners, he conceded, had "sold the idea that there are simple answers to complex questions — which there aren't." No body source for this edition published a fresh economic defense of the 2016 vote.

Andy Burnham, the former Manchester mayor who won a by-election last week and is the runaway favorite to succeed Starmer, will inherit the ledger. Labour's leadership contest begins July 9.