The scale of the challenge facing Rachel Reeves ahead of the autumn budget has been laid bare by a rise in Britain’s national debt to the highest levels since the 1960s and a collapse in consumer confidence.

Figures from the Office for National Statistics (ONS) showed the government’s outstanding debt pile reached 100% of gross domestic product in August, the highest level since 1961, as monthly borrowing rose by more than expected.

Labour has warned repeatedly that the economic inheritance from the Conservatives will require “painful” decisions ahead of the 30 October budget, including tax rises and cuts to welfare benefits and other spending.

Figures released by data provider GfK on Friday revealed a sharp fall in consumer confidence in September to the lowest level since March, blaming households’ concern about Reeves’s cuts to winter fuel payments and the prospect of further spending restraint at the budget.

“Consumers’ reaction to the government’s warnings shows that Reeves will need to be careful to not overdo the fiscal tightening next month,” said Elliott Jordan-Doak, a senior economist at the consultancy Pantheon Macroeconomics.

According to the latest snapshot from the ONS, government borrowing – the difference between public sector spending and income – was £13.7bn, an increase of £3.3bn on the same month a year earlier, and the third highest August deficit since monthly records began in January 1993.

The national debt – the sum total of every deficit – rose by 4.3 percentage points during the year to August to 100% of GDP, meaning an overall debt pile equal in sie to the annual value of everything produced in the economy.

Darren Jones, the chief secretary to the Treasury, said the figures demonstrated the challenging state of the public finances left by the Conservatives, which would force Labour to take “tough decisions” to rebuild the economy.

“When we came into office, we inherited an economy that wasn’t working for working people. Today’s data shows the highest August borrowing on record, outside the pandemic. Debt is 100% of GDP, the highest level since the 1960s,” he said.

The figures came amid growing pressure on the government to ease tax increases and spending cuts pencilled in for the 30 October budget, after Keir Starmer told the public to expect “painful” decisions after finding what Labour called a £22bn hole in the public finances.

Reeves announced in August she would scrap winter fuel payments for most pensioners, shelve plans for social care reform and axe road, rail and hospital investment as the first stage of a plan to reduce borrowing.

However, concerns are growing within Labour ranks that the downbeat tone is damaging the government, while economists have warned that measures hitting consumer confidence could hurt growth and jobs.

The latest snapshot of the public finances from the ONS showed that while tax receipts grew strongly in August, this was outweighed by higher expenditure – largely caused by benefits rises and higher spending on public services owing to increased running costs and pay.

While official figures had put the debt ratio above 100% last year, the ONS said revisions meant this was the first time since 1961 the reading had equalled the size of the economy.

Matt Swannell, the chief economic adviser to the EY Item Club, said: “At what is almost the halfway point of the fiscal year, the UK’s fiscal position remains challenging, and Treasury analysis suggests that the situation may deteriorate further over the remainder of the year.

“The government will likely have to increase spending over the next few months, due to a combination of accepting the recommendations for higher pay increases from public sector pay boards and non-labour cost overruns across a range of government departments.”

Keir Starmer won the election because of a ruthless focus on winning over people who voted Conservative in 2019, but the party has been left with a “fragile coalition” of supporters who will abandon it if it fails to deal with the cost of living crisis and the NHS, a thinktank has said.

In a report by Labour Together, an influential Starmerite thinktank, researchers concluded voters had “cautiously hired” the prime minister “on a trial basis”, and he was “liable to prompt dismissal” if his government deviated even slightly from focusing on voters’ priorities.

The thinktank reported their findings to key No 10 figures, including Pat McFadden and Morgan McSweeney, in a Cabinet Office meeting last week.

The researchers, who are regarded as the government’s “critical friend”, said they were honest and direct about the challenges they believed lay ahead for Starmer’s top team. Officials were told that if the government did not deliver for voters, who have become more transactional than ever, they could easily face the same fate the Conservatives did after the 2019 election.

The report is based on a survey of 10,000 people across the country in polling and small focus groups, asking them why they voted the way they did. Labour Together had decided to launch this assessment of Labour’s performance once the general election was called in May, regardless of the result at the ballot box.

“Middle Britain” voters decided the outcome of the 2024 general election, the analysts said. They summarised this group of voters as being in the ideological centre of the country, slightly to the left on economic issues and more “authoritarian” on cultural issues.

The report notes it was Middle Britain’s “desire for change that mattered most” in the election, with Alex, a constituent from Leigh and Atherton, in north-west England, telling a focus group: “I’ve always voted Conservative, but it got to the point where I was thinking there’s got to be something better than this.”

However, Labour Together notes the party’s focus on demonstrating to people in “Middle Britain” that it shared their values was not without its cost, with Labour losing seats in Bristol West and Islington North to its left; Thangam Debbonaire and Praful Nargund lost to the Green party’s co-leader Carla Denyer and Jeremy Corbyn respectively. Jonathan Ashworth, the chief executive of the thinktank, also lost his Leicester South seat to the independent MP Shockat Adam.

While the research does not include analysis of independent seats, which is expected to come at a later date, it does note that many traditional Labour voters in Muslim communities backed independent candidates because of Labour’s position on the war in Gaza. It highlights a strong correlation between a decline in Labour’s vote share and the proportion of Muslims in a constituency.

“The depth of feeling about the situation in some, particularly Muslim, communities was profound,” the report states. “Its impact on voting intention was understated ahead of the election, in part because high-quality polling of ethnic minorities is rare.”

The issue cost Labour four seats, which went to independents. In the 17 seats where independent candidates finished second, Labour holds a lower average majority than it does where the Conservatives finished second.

However, the thinktank argues Labour’s biggest threat comes from the right, with the Tories being Labour’s biggest opponent, followed by Reform. Labour holds only an average majority of 14% over the Tories across all seats where they finished second. With Reform, Labour’s majorities average about 25%.

Morgan Wild, the chief policy adviser at Labour Together and co-author of the report, said: “Middle Britain needed to see that Labour had changed since 2019. It had. The 2019 Conservative voters it attracted were in the centre ground of British politics – without them, Labour simply could not have secured this decisive victory.

“Elections are won in the centre ground – a basic electoral truth Labour has a habit of forgetting. It mustn’t do so again: instead, the government must stay relentlessly focused on voters’ top priorities.”

A government figure said: “The findings reinforce that if we take our eyes off why voters elected us, we won’t be here in five years.”

More than 2,000 jobs have been axed and dozens of government construction projects could be paused as ISG, one of the UK’s largest contractors, fell into administration.

In the biggest collapse of a UK construction company since Carillion, administrators EY confirmed on Friday that ISG had ceased trading with immediate effect, with the closure of all of its sites.

It confirmed that most of the 2,400 people it employed in the UK would be made redundant with immediate effect, with only 200 staff retained to assist administrators.

ISG is involved in 69 live central government schemes, including several projects as part of the Ministry of Justice’s plan to increase the capacity in Britain’s prisons by an extra 20,000 spaces. It is also working on schemes for the Department for Work and Pensions and several school building projects.

The Cabinet Office said it had implemented “detailed contingency plans” and departments were working to ensure sites were safe and secure.

ISG is the sixth biggest construction contractor in the UK by turnover, with revenues of £2.2bn. In 2018, Carillion, the UK’s second-biggest contractor, collapsed owing suppliers £7bn.

EY said it had been appointed as administrator to ISG’s eight trading titles, and ISG’s full UK construction services had ceased to trade with immediate effect.

It said the UK business had experienced significant liquidity constraints in recent months and because of market conditions a sale or additional funding could not be secured.

In an email to staff on Thursday, first reported by Construction Enquirer, ISG chief executive, Zoe Price, apologised and said the group’s cashflow was affected by large lossmaking contracts secured between 2018 and 2020.

She added: “Trading out these projects has had a significant effect on our liquidity. So even though we have been profitable this year, our legacy has led us to a point where we have been unable to continue trading.”

As well as the closure of its offices and construction sites, subcontractors have been stood down from their work.

Data from the construction analyst Barbour ABI has estimated that ISG is involved in live government construction projects worth £1.8bn. These include 22 live projects with the Ministry of Justice, including a number of prison schemes such as the £300m extension to Spring Hill, in Buckinghamshire.

This comes only weeks after the government let out 1,700 offenders early to ease overcrowding.

ISG also has contracts with high-profile private clients such as Apple, Google and Barclays.

There were reports earlier this year that the company was facing cashflow problems, and the chief executive, Matt Blowers, and the finance director, Karen Booth, left the company in February and March respectively.

In July, it reported that it had found a potential buyer, with the investment firm Antipodean Holdings in discussions over a takeover.

Antipodean Holdings said in a statement on Friday that it was ready to strike a deal to secure jobs and was committed to a deal until ISG stopped communicating with it on 12 September.

Addressing this, the administrators said: “We wish to be clear to employees, suppliers, and customers that it was not possible to conclude a sale as the potential purchaser could not, despite repeated requests of them to do so, adequately demonstrate that they had the funding needed to recapitalise the business and keep it solvent.”

It added that directors also looked at refinancing the company but were unable to complete this.

Fresh proposals to allow young people to move between the UK and the EU will be presented to the British government within weeks, in what is seen as a key early test of Labour’s “reset” in relations with Brussels.

Informed sources say the first draft of a new version of Ursula von der Leyen’s April proposal has already been discussed by member states and will be put to a working group in Brussels next week.

Among possible changes could be the removal of four-year student exchange programmes in which the students pay the home fees of the university they attend, something UK universities have said is not an option.

If finalised next week, member states will then instruct the European Commission to make a fresh offer to the UK.

The previous, Conservative, government knocked back similar proposals earlier this year but EU officials hope the new Labour administration will revisit the issue. They warn privately that another rejection could jeopardise this government’s desire to sign new agreements on defence and agriculture.

Some European diplomats say they are “dismayed” that Starmer has not already reversed the British government’s position on a youth mobility scheme, and it would be pointless to open more complex negotiations on defence or trade without agreeing this first.

Some point out that the UK has yet to make any proposals to Brussels for what it might want in any security or agricultural pact, and criticise the prime minister for ruling out more significant change, such as rejoining the customs union.

One said: “The red lines are almost like Theresa May’s, it is difficult to see what has changed.”

Some believe Britain will struggle to make major agreements with Brussels given its lack of leverage.

“The key to understanding the EU-UK relationship is that we are much less concerned with the UK than the UK is with the EU, especially post-Windsor framework,” said one diplomat, referring to the 2023 deal on trading arrangements in Northern Ireland.

“There is absolutely room for improvement in the relationship but the biggest pain has been removed and the UK is not top of the agenda. If Keir Starmer wants us to come to the table, don’t expect us to drop everything to have that conversation.”

The Cabinet Office, which is handling negotiations with the EU, declined to comment. A government spokesperson said last month: “We are not considering an EU-wide youth mobility scheme and there will be no return to freedom of movement.”

Starmer has promised a significantly closer trading relationship with the EU, and has prioritised a defence and security pact, which officials say can be agreed quickly, and an agreement on agricultural products, which is likely to take longer.

Since taking office, Starmer has visited the German chancellor, Olaf Scholz, in Berlin and the French president, Emmanuel Macron, in France, and he hosted 50 leaders from across the continent for the European Political Community meeting at Blenheim Palace in Oxfordshire.

In April, the commission proposed a visa scheme that would allow EU and UK citizens aged between 18 and 30 to stay for up to four years in each other’s countries.

Controversially, it also suggested students on the scheme could pay the home fees of the university they attended, but UK universities have made clear this would be unacceptable because their stretched finances could not cope with the loss in revenue. UK students pay around £9,000 a year in fees, but overseas students can pay from £16,000, in Scotland, to up to £59,000 at Oxford University.

EU sources insist the scheme would not amount to free movement, given that the visas would apply for only a limited time.

Some countries believe reducing the proposed length of youth visas from four years to two, in line with other schemes that the EU has with Canada and Australia, could break the impasse.

Four Greenpeace activists who staged a “no new oil” protest on the roof of Rishi Sunak’s North Yorkshire manor house have had charges of criminal damage thrown out.

The activists said “justice and common sense” had prevailed after a judge on Friday ruled the evidence against them was “tenuous” and they had no case to answer.

They also called on Keir Starmer to reverse “draconian, anti-protest” laws introduced by the previous government.

Adrian Lower, a district judge sitting at York magistrates court, ruled there was no case to answer against the four protesters.

He said his full ruling would follow but described the evidence against the four as “tenuous”.

His judgment came two months after a criminal damage trial against the four was opened and then adjourned on the second day.

It heard that 15 roof tiles on the former prime minister’s house at Kirby Sigston, near Northallerton, were damaged during the rooftop demonstration in August 2023. Six were Welsh blue tiles and nine were Westmorland tiles, the court was told.

The repair cost was £2,937.96 including VAT, the court heard, and tree surgeons who were not able to work at the property because of the protest still charged their daily rate of £1,450.

Mathieu Soete, 38, of Antwerp, Amy Rugg-Easey, 33, of Newcastle, Alexandra Wilson, 32, of St Ives, and Michael Grant, 64, of Edinburgh, pleaded not guilty to criminal damage.

A defence barrister argued there was insufficient evidence to prove that the protesters had damaged the tiles. Owen Greenhall said the defence case was that “these defendants did not cause any damage, that it was pre-existing”.

He told the court: “If there was any damage, it certainly wasn’t done intentionally. These defendants were not aware of the risk of damage. They were taking care.”

Sunak and his wife, Akshata Murty, and their two daughters were away from the house, on their summer holidays, when the four activists climbed on the roof and covered one side of the building in black fabric, in protest at the decision to license “hundreds” more oil and gas drill sites in the North Sea.

The prosecution argued that the defendants were “reckless” when they climbed the roof for what was a five hour protest.

Delivering a statement outside the court building, Grant said: “We have become a country that regularly sends peaceful protesters to jail, with some facing years behind bars for trying to preserve a habitable planet for us all. This has to stop.”

He said peaceful protest was a vital part of democracy which had brought equal votes for women, the right to a weekend and bans on commercial whaling and fracking.

“For Keir Starmer’s government we have a simple question: how much longer will they sit back and watch as this draconian crackdown on dissent keeps unfolding on their watch.”

Grant said the process had been difficult and long but they were glad of the outcome. Others were not so lucky and were in jail, he said, “for doing what we were trying to do, for trying to preserve a habitable planet.”

Some people have criticised the protesters for targeting a family home but Grant said they knew Sunak and his family were on holiday in California when they staged the protest. “We knocked on the door. There was nobody in the building and we knew that.”

During the trial, the Sunak family’s personal chief of staff, Scott Hall, said the property was “well-maintained” and staff “would have been aware of any damage to the roof”.

But in cross examination he agreed there did appear to be some cracks in areas of the roof away from the protest that he had not been aware of, and that some of the house’s window frames appeared to have peeling paint.

Nigel Farage has predicted he can win the next general election at a packed Reform UK conference that announced a new structure for the party but also leaned heavily into hard-right tropes and occasional conspiracy theories.

“We can win the next general election just with the numbers of people that agree with our principles,” Farage told cheering supporters in Birmingham.

“What we have to do is to be credible. What we have to do is be on the ground everywhere. What we have to do is to show that we can bring success after success after success. If we do those things, we genuinely can.”

At the gathering – which included repeated attacks on immigration, diversity and green policies, and calls to “put British people first” – Farage promised to professionalise the party and end its status as a company majority-owned by him.

Instead, he said, it would become a mass-owned non-profit organisation with “significant” control by members – although he did not set out what this would entail.

Ahead of the start of Labour’s conference on Sunday, Farage later said that the governing party was Reform’s prime target, referring to a recent poll suggesting 26% of Labour voters would seriously consider or consider voting for Reform in future.

“I think these big themes around family, community, country appeal very much to an old Labour target,” he told journalists.

The first proper conference for the successor to the Brexit party, which won the third-biggest vote share in July’s general election, attracted about 4,000 people to the National Exhibition Centre.

The second day of the event, Saturday, is aimed at helping to organise new branches, while Friday was devoted almost entirely to speeches from the main conference arena, with Farage completing a lineup of all five Reform MPs elected on 4 July.

A sequence of the speeches took on a populist and hard-right tone, with some echoing far-right conspiracies. Policies set out included the mass deportation of all overseas nationals in UK jails, an end to foreign aid and the scrapping of diversity-related jobs in the public sector.

While Farage launched attacks on Labour and the Conservatives and echoed attacks on government “sleaze” – including by brandishing a pair of glasses – much of his address was aimed at rallying Reform members to join the professionalisation process and campaign in the local elections across England next May.

Farage, who walked on to the stage to the song Without Me by Eminem, said the aim was to win “hundreds and hundreds and hundreds” of councillors, as a bridgehead for future general election success, saying this would be modelled on the Liberal Democrats.

Later, he told journalists that Reform had expected to poll more than it did in the general election in July, saying that the last week of the campaign was a “disaster” for his party against the backdrop of candidates who had not been vetted properly.

“It was just a disaster. We had expected the poll 5% more than we did, and the electorate punished us. The electorate punished us, for having these bad apples in there,” he added.

In earlier speeches, Rupert Lowe, the Great Yarmouth MP, attacked organisations including the UN, World Economic Forum and “Bilderbergers”, whom he said were trying to subvert the UK.

He condemned government actions, including “inflicting an experimental jab on millions of people” during the Covid pandemic, and said the Equality Act had allowed minorities to “impose their will and views on the majority”.

Another Reform MP, Lee Anderson, reiterated some of the comments about Sadiq Khan, the London mayor, which caused him to lose the Conservative whip, saying of Khan: “In my opinion he has given our capital city away and he should be thoroughly ashamed of it.”

Anderson also ripped up a letter telling him to pay his TV licence fee, to cheers from the crowd.

On Friday morning, the conference loudly applauded a speech from the former soldier and reality TV star Ant Middleton, who warned that mass civil unrest was imminent because the British identity was being “eradicated”.

Middleton, who formerly appeared on Channel 4’s SAS: Who Dares Wins, also said that unnamed forces were trying to distract people from the country’s problems, so “they can control you”.

“What’s British identity? British culture. British history,” he said. “Why is that being eradicated? Why is that being trampled over?”

This process, he said, would lead to frustration, then anger and finally violence: “We are at a very important and crucial stage before it teeters into civil unrest. We’ve all seen it. I don’t need to mention what it is. We’ve all seen it.”