Three years on, Britain still lags behind other global economies

This photo dated December 9, 2020 shows the flags of the Union Jack and the EU ahead of Britain's prime minister's meeting on post-Brexit trade deal with European Commission President, in Brussels. Three years after its departure from the European Union, Britain is yet to benefit from the Brexit dividend that was promised for its economy, as it lags its peers on multiple fronts, including trade and investment.

Britain left the EU on January 31, 2020, but remained in the bloc's single market and customs union for 11 more months.

On that day, Boris Johnson, prime minister, said the country could finally fulfill its potential and that he hoped it would grow in confidence with each passing month.

The opposite has happened so far, with a range of indicators showing under-performance compared to other economies.

Opinion polls show Britons regret leaving the EU more than those who don't. A survey conducted on Monday by UnHerd showed that this was the case in all but three of 632 parliamentary constituencies analyzed.

The government, led by the Prime Minister Rishi Sunak, says Britain is prospering with new freedoms.

Finance Minister Jeremy Hunt challenged the talk of decline last week, saying thatBrexit offers a brighter future with room for measures that will attract investment in areas such as the green economy and tech.

Many economists say leaving the EU is not the sole cause of Britain's woes - the country was hit hard by the coronaviruses and the surge in gas prices after Russia's military operation in Ukraine - but it is a factor that can explain recent underperformance.

It was more than a slow burn. John Springford, deputy director at the Centre for European Reform think tank, said it was a serious reduction in economic performance.

He said that if you impose barriers to trade, investment and migration with your biggest trading partner EU, you're going to have a big hit to trade volumes, investment and GDP.

Britain was the only Group of Seven advanced economy to regain its pre-pandemic size in late 2019 at the end of September last year, the most recent period covered by data.

READ MORE: EU eyes repatriate more people to Africa, Middle East, Asia.

The International Monetary Fund predicted Britain's economy will shrink by 0.6 percent this year, in contrast to predictions of growth across the rest of the G7 on Tuesday.

Springford estimated that Britain's economic output fell by around 5.5 percent as of mid- 2022 compared with what it would have been without the EU, based on a doppelganger model in which an algorithm selects countries whose economic performance matches pre-Brexit Britain.

There is a long-running net cost to leaving the EU, according to the government's forecasting organization, the Office for Budget Responsibility, and the Bank of England.