HS2: Heseltine says project would 'rebalance' UK wealth
The HS2 rail project would help "rebalance" the UK, former deputy prime minister Lord Heseltine has said.
The senior Tory called the high-speed line a "really imaginative project" to spread the prosperity of London and south-east England around the UK.
Speaking about cost, he said too much faith had been put in analysis produced by "guys with slide rules".
Meanwhile Prof Henry Overman, of the London School of Economics, has said HS2 is "not particularly good value."
HS2 would link Birmingham and London, with tracks to cities including Leeds and Manchester built in a second phase.
Ministers argue HS2 will boost the UK's economic prospects and slash journey times to and from London.
Lord Heseltine said south-east England was growing faster than the rest of the UK and that caused environmental problems such as the need for new homes in the countryside.
And he said other areas were not sharing in the "well-being feeling" enjoyed by the South East.
Speaking about HS2, he said: "Here's a really imaginative project in order to do something to rebalance the United Kingdom."
The project could help put a "sense of can-do back in to those great towns of the Midlands and the north that made this country in the first place," he added.
According to the current government estimate, the infrastructure project will cost £42.6bn at current values, plus more than £7.5bn for rolling stock.
But Lord Heseltine told BBC Radio 4's Today programme the rolling stock should not be included in the debate on cost because "the private sector can pay for the trains".
Various cost-benefit predictions for HS2 have been produced, but Lord Heseltine said these were "mumbo-jumbo".
He said the "guys with slide rules" simply do not know what the economic benefits will be.
In a speech later, he is expected to warn that future generations will judge those in power today harshly if they fail to deliver the new line.
"HS2 is about our country's competitiveness for a half century or more," he will tell the Royal Town Planning Institute.
"All over the world governments are making decisions about a future which they cannot predict but in which they believe."
HS2 has commanded cross-party support from its inception but Labour appeared to change its tone recently, saying it would not give the project a "blank cheque".
However, Lord Heseltine will warn sceptics: "Not many of those in power to make decisions will be around to judge the world of the HS2 but others of younger generations will judge us."
Professor Overman, a member of an HS2 analytical challenge panel, set up to provide "independent expert scrutiny", said available evidence suggested the scheme was "not particularly good value for money" compared to other transport projects.
"It may well even be poor value for money compared to other alternatives that address exactly the same set of problems," he said.
"The case for improvements on the existing lines is actually pretty good in terms of the benefit-cost ratio, which is the way some of us like to look at these things."
A recent report by KPMG suggested the new line could generate £15bn a year in "productivity gains" for the UK economy - with Greater London and the West Midlands the biggest beneficiaries.
The accountants behind the report and Transport Secretary Patrick McLoughlin are due to appear before MPs on 26 November to defend their economic justifications for the railway.