LONDON: A decade after Britain's June 23, 2016 referendum vote to leave the European Union, the UK is several percent poorer than it would have been had the country stayed in the bloc, a prominent British economist says.
Jonathan Portes, professor of economics and public policy at King's College London, says Brexit has had a significant negative impact on the economy, as economists predicted prior to the vote - although the Bank of England says the impact was less damaging than initially thought.
While the precise figure of the dent to Britain's GDP since the UK's withdrawal is subject to debate, other European countries have also faced economic difficulties over the same period.
Britain's official budget forecasters estimate the economy would be 4% smaller 15 years after Brexit than if the country had remained in the EU.
The U.S.-based National Bureau of Economic Research projects an even larger hit, of 6 to 8%, with investment - which is crucial for future economic growth - down by 18% compared with a no-Brexit scenario.
The referendum also triggered years of political turbulence.
Then-prime minister David Cameron, who called the referendum amid discord in his own Conservative Party, resigned the day after the result on June 24, 2016 after campaigning to remain in the EU.
Four of his Conservative colleagues followed him into Downing Street as prime minister - Theresa May, Boris Johnson, Liz Truss and Rishi Sunak - before Keir Starmer led the Labour Party to victory in the 2024 general election, following 14 years in opposition.
Portes said Brexit has aggravated political instability in the UK, although the rise of what he called far-right parties was also visible elsewhere in Europe and could not be blamed on Brexit alone.
One of the central promises of the 'leave' campaign was to take back control of immigration by ending free movement from the EU, and while free movement has ended, Portes says structural pressures, labour shortages, the COVID-19 pandemic and the war in Ukraine have pushed immigration to higher levels than before Brexit.
While this has cushioned the economic impact of leaving the EU, it was not what many voters thought they had supported, he says.
Reform UK leader Nigel Farage has enjoyed political success in recent elections and disrupted the traditional dominance of Labour and the Conservatives - despite the widely perceived failure of Brexit, for which he was a key campaigner.
Portes said Farage has avoided responsibility for Brexit by staying out of government, while the Conservative Party has absorbed much of the blame and become less of a broad coalition.
Public opinion has shifted, with a broad consensus that Brexit had failed even among some who voted for it, Portes says, although there is no agreed path back to a structurally closer relationship with the EU.
While ties have strengthened since Labour were elected, with a new trade and defence agreement signed in 2025, Portes says the EU itself has been weakened by losing the UK.
European leaders should treat reassociation with Britain in some form as a greater priority, he says, particularly given a multitude of geopolitical and security challenges.
