Sir Keir Starmer and Rachel Reeves campaigned on a promise to make Britain the fastest-growing economy in the G7.

But new data shows that the country has in fact crashed near the bottom of the growth table in the months since the election.

GDP growth plunged from 0.5pc in the second quarter of the year to 0.1pc in the third, according to the Office for National Statistics (ONS). The figures cover July to September, the three months after Labour won the general election on July 4.

It marks the first clear indication of the new Government's impact on the economy.

In the first six months of 2024, Britain had the fastest rate of growth in the G7. Officials described the UK economy as "going gangbusters".

Yet when comparing performance in the third quarter, the UK was the second worst in the G7.

Growth in the UK was slower than Germany (0.2pc), Japan (0.2pc), France (0.4pc) and the US (0.7pc). Canada is yet to report but analysts expect growth of around 0.25pc. Only Italy did worse than Britain, with no growth in the third quarter.

"After bouncing back from recession earlier this year, Britain's recovery is already running out of steam," says Simon Pittaway, senior economist at the Resolution Foundation.

The ONS said the slowdown was broad-based and economists and business groups placed the blame squarely on Starmer and Reeves.

"Uncertainty ahead of the Budget probably played a big part, with firms widely reporting a slowdown in decision making," says Ben Jones, lead economist at the Confederation of British Industry (CBI).

"The Budget has set off warning lights for business."

Lindsay James, investment strategist at money manager Quilter, says of the slowdown: "Much of this will have been as a result of the gloomy messaging that was persistent in the run-up to the Budget, causing consumers and businesses to pause spending and await what pain was to come."

Both Starmer and Reeves began talking down public finances and warning of major tax rises almost immediately after winning power, casting a pall over the country.

Less than a month after coming to power, Reeves warned of a £22bn black hole in the public finances and immediately scrapped winter fuel payments for 10m pensioners.

Shortly after that, Starmer warned that the October Budget would be "painful".

In the months leading up to the Budget, key Labour figures including Ms Reeves made repeated warnings that tax rises would be necessary.

David Bharier, head of research at the British Chambers of Commerce (BCC), said business confidence slumped "amid a spike in anxiety over tax and employment policy".