The plan to rescope HS2 to a “Euston-Crewe core” would accelerate delivery, and ensure a substantial financial return to the Treasury, while recognising current fiscal constraints.

Rescoped proposals have been submitted to the Treasury ahead of the spending review with a warning the project is at a crossroads that could determine its failure or success.

Industry backers argue the extension to Crewe would add urgently needed national transport capacity between London, the West Midlands and the North West.

The HSRG is calling on the Government to ‘un-freeze’ the planned connection from the West Midlands to Crewe.

Without this, the group warns HS2 would fail to relieve pressure on the West Coast Main Line at its biggest pinch-point.

It also proposes that the Government fund and delivers a scaled-back, cost-effective Euston Station with a simple functional design that could be delivered ahead of the wider regeneration ambition for the area.

HSRG is advocating for a six platform design, with the option for future expansion retained.

Under present plans, Euston looks set to be delivered many years after the opening of HS2, with trains terminating at Old Oak Common station in North London.

The group estimates that the cost of delivering at both ends of the line could be reduced by 35%, unlocking potential savings of £3bn – £4bn compared to previous estimates.

HSRG estimates that a concession let for a London–Birmingham & Crewe railway line would generate between £7.5bn – £10bn, a significant return for taxpayers.

But it warns that without Euston station and the connection from the West Midlands to Crewe, the value of a HS2 concession to HM Treasury would likely be halved.

Dyan Perry, chair of HSRG, said: “HS2 is at a crossroads. If delivered correctly, it will unlock national transport capacity, generate a multi-billion pound return to the Treasury, drive economic growth across the UK and enhance regional connectivity.

“However, if cut short, the Government risks wasting substantial investments to date, short-changing the national account and squandering HS2’s far reaching socio-economic benefits.

“HS2 has already stimulated significant investment in the UK’s supply chain, workforce skills, and infrastructure expertise to name just a few benefits.

“To secure the long-term advantages of a modern, high speed rail network, we strongly urge the Government to adopt our recommendations and take decisive action to restore financial control and accelerate delivery. By investing in our infrastructure now, we set the UK up for long term growth and economic success.”