Britain’s economy will be closer to Guyana than the US on some measures in a decade’s time, economists have warned.

The research by the Centre for Economics and Business Research (CEBR) is a blow to Sir Keir Starmer’s pledge to improve living standards.

The CEBR predicted that the UK’s growth in GDP per head – a measure of living standards – will be among the weakest in the G7 over the next five years.

Britain is set to remain in 22nd place in the global league table for GDP per head in 2029.

The UK is expected to go up one place by 2039 with GDP per head expected to be $86,141 (£68,800).

But this would be closer to Guyana’s GDP per head of $78,695, than the US where it is projected to stand at $148,411.

Pushpin Singh, of the CEBR, said the figures showed Britain risked “falling behind in the global economic race”.

He told the Telegraph that GDP per head was “forecast to lag far behind the US and inching closer to emerging markets like Guyana, highlighting a potential stagnation in living standards under Sir Keir Starmer’s leadership”.

He said: “The way the UK economy has fared over the last five years, I would say we are much more similar to France than we are to the US. One key thing that is driving the US growth is productivity, which has been off the charts since the pandemic.

“UK welfare spending is still not as bad as France. But are we on the road there? I think so in terms of elevated welfare spending, tax receipts not being enough to make up for that welfare spending and other spending commitments such as the NHS and other civil service sector spending. And debt as a share of GDP is slowly ballooning up as well.

“Productivity growth has been a huge issue in the UK, specifically within the civil service.”

The Prime Minister has made boosting living standards across the country a priority for his premiership.

But he admitted earlier this month that it “will take some time” before they improve.

Meanwhile, the Government has faced an ongoing backlash over Chancellor Rachel Reeves’s tax-hiking Budget in October.

A Treasury spokesman said: “We delivered a once-in-a-lifetime Budget to stabilise the public finances and fix the foundations of our crumbling public services without increasing income taxes on working people.

“Now that we have wiped the slate clean, we can focus on delivering our Plan for Change and kickstarting economic growth which is how people will feel better off. The OBR has concluded economic growth will increase to 2pc in 2025 and the OECD upgrade will mean the UK is the fastest-growing European economy in the G7 over the next three years.”