The construction industry and leading bodies in the north and midlands have all urged the prime minister to “get HS2 done” in order to kick-start the infrastructure revolution the British economy needs.

The urgent high-level industry response followed a leaked report that claimed the cost of HS2 could balloon to over £106bn.

The leaked report, seen by The Financial Times, has also called for work on the second phase of the link – from the West Midlands to Manchester and Leeds – to be put on hold for six months to explore whether it could be made up of a mix of standard and high-speed rail.

The unpublished report warns there is a “considerable risk” that costs could rise by another 20% to over £106bn compared with the last estimate, which priced the project at a potential £88bn. The original budget for HS2 was £34bn.

The latest report follows an earlier leak last November of the government-backed Oakervew review, recommending that HS2 should go-ahead in full, building the full Y-shaped line, which would create two lines north of Birmingham: one to Manchester and the other to Leeds. They would then join the west and east coast main lines.

However, the latest leaked report claims further work is needed to assess what impact on growth the project will have in the regions as it is “hard” to determine whether there will be any economic benefits.

Suggestions that the second phase of HS2 could be watered down, once the first leg from London to Birmingham is completed, prompted dismay in the north and the midlands. 

Andy Burnham, mayor of Greater Manchester, told the BBC: “To me that would be the same old story. London to Birmingham, money is no object, and then all the penny pinching is done in the North of England. That would not be acceptable to me, and I’m sure wouldn’t be acceptable to many other leaders across the north.”

Henri Murison, Northern Powerhouse partnership director, said: “This is a seminal moment in the modern history of the UK. Any failure to seize this opportunity would be a betrayal of the North, and the promise of a Northern Powerhouse. Time to level up the country and close the north-south divide.”

Midlands Connect chairman Sir John Peace warned that any delay or downgrade of HS2 would be a betrayal of the Midlands and the North.  

“The tone of today’s Oakervee review leak in the Financial Times is of serious concern,” said Sir John. “We need a modern, fast and reliable railway to link our great towns and cities sustainably. Any further delay or downgrades of the project will send the wrong message to the people of our region, but it will also send the wrong message to foreign investors who see Britain as an opportunity for growth after Brexit.” 

The Association for Consultancy and Engineering (ACE) have co-signed a joint industry letter to the prime minister, highlighting the importance of the major project in supporting an "industrial renaissance" in the Midlands and the North, creating more than 30,000 jobs, and urging a commitment to HS2 that "demonstrates this country's ambition to remain at the forefront of global engineering, infrastructure and construction delivery.”

Covered in The Times and the Birmingham Mail, the letter was signed by a number of business leaders including ACE chief executive Hannah Vickers alongside Costain, Mott MacDonald, Ramboll, WSP, contractors Balfour Beatty, Skanska, Morgan Sindall, Mace, Sir Robert McAlpine, and business groups CBI, FSB, Build UK and CECA.

Hannah Vickers, ACE chief executive, said: “Whilst we await to see what the formal publication of the review into HS2 brings, we need to remind ourselves of what’s important. This isn’t about overall budget, it is about value for money. It is not about quicker journey times, but adding much needed capacity across the entire rail network. Without it, the Northern Powerhouse Rail and Midlands Engine will be ineffective as the three projects are, in fact, symbiotic. 

“This isn’t about commuting to London, but rebalancing economic activity across the country. The government has committed the UK to achieving Net Zero emissions but without high speed rail taking passengers away from internal flights, and new services encouraging people and freight to travel by train, the target will remain out of reach.

“The fact remains that if HS2 was cancelled we would only have to invent a very similar project in a few years’ time as the fundamental issues of capacity, connectivity and economic rebalancing of our economy won’t be going away any time soon.”

Marie-Claude Hemming, director of external affairs for the Civil Engineering Contractors Association (CECA), said: “HS2 is vital to this country’s future, and must act as a springboard for the infrastructure revolution the government has promised. There are simply no alternative shovel-ready projects on the same scale in the pipeline, or other means of delivering growth in the economies of the Midlands and the North of England as rapidly, as this once-in-a-generation scheme.”

The Rail Industry Association and senior business leaders also urged the prime minister to consider the importance of HS2 to Britain’s future prosperity, claiming that any hiatus would have a devastating impact on jobs and risk delaying the infrastructure revolution by a decade.

The first leg of HS2, linking London Euston station to central Birmingham, was due to open by the end of 2026 but a separate report by the HS2 Ltd chair, Allan Cook, forecast that could be pushed back until 2031. The second phase, linking the line on two branches to Leeds and Manchester, was originally due to open in 2032-33, but transport secretary, Grant Shapps, revealed in the autumn that HS2 Ltd now believes the full line may not be open until 2040.

Shapps told Sky News today (Monday) that the “massive decision” on whether to go ahead with HS2 “needs to be fact-based” and would be made shortly. Shapps said he had asked Oakervee to “give me the facts, give me the data, give us the information so we can make a proper informed decision.” He said he had “a relatively neutral point of view, adding: “We’ll be making a final decision, along with the prime minister and the chancellor, on this very shortly.”

The Oakervee Review is expected to return its findings into the major project in the coming weeks, while the National Audit Office will also return the results of its investigation by the end of January. Following this, the prime minister is expected to make a final decision on the project which has been the subject of intense public criticism by campaigners and environmentalists in the last few weeks.