George Osborne would need to end national bargaining and close three Whitehall ministries to meet his spending plans, a gaggle of vocal rightwingers claimed yesterday.

In a stark warning of future economic pain, the Tory-friendly Taxpayers Alliance (TA) urged politicians to pledge a whopping £50 billion in extra spending cuts.

A TA report published today calls for abolishing the “triple-lock” that protects the value of pensions, freezing benefits for two years and slashing nearly £5 billion from central grants to Scotland, as well as snatching back winter fuel payments and bus passes from all but the poorest pensioners.

Labour has claimed that Mr Osborne would need to slash spending by £70bn to hit his target of running a surplus by the end of the next Parliament but Tories insist they can reach this target with cuts of “just” £30bn.

The Office for Budget Responsibility has said Mr Osborne’s forecasts would result in spending falling to just 35.2 per cent of GDP — its lowest level since the 1930s.

But TA suggested a further reduction to 31.7 per cent — a figure that would require the axing of the HS2 rail link and the Department for International Development and raising the retirement age to 67.

“The politicians seeking our votes owe it to all taxpayers to come clean about what spending the country can and cannot afford,” chief executive Jonathan Isaby smarmed.

But TUC general secretary Frances O’Grady thanked the “shadowy” alliance for publishing their “vicious cuts hits list.”

She said: “If the Chancellor were to achieve the cuts he seeks these are exactly the kind of attacks on pensioners, the vulnerable and vital investment he would need to make.

“In particular, they show he will come after public-sector workers with job cuts, pay freezes and attacks on union organisation.”

And Left Economic Advisory Panel convenor Andrew Fisher warned that the plans would plunge British society into devastation on a new level.

“If the Tories are elected in May, it is clear that a turbo-boosted Thatcherism will be implemented to roll back the state to an extent never achieved in a major democratic economy.”

The prospect of scrapping public-sector national pay bargaining to save £5.8bn set alarm bells ringing among trade unionists.

Unison assistant general secretary Karen Jennings blasted: “Just days after International Women’s Day, the suggestion from the Taxpayers Alliance that national pay bargaining should be scrapped is a slap in the face to women everywhere.

“Around 70 per cent of public service workers are women and such a move would reverse the great strides unions have made towards gender equality.

“National pay bargaining ensures equal pay for women, improves their position in the workforce, and gives workers greater flexibility to move around the country.”