Many of us have been blasting the politics of austerity because there has never been one fact to support it especially during an economic crisis, but England's grand poobah has been leading the austerity charge and hasn't backed down. The IMF is just the latest organization to throw could water on his predictions.

George Osborne's drastic deficit-cutting programme will have sucked £76bn more out of the economy than he expected by 2015, according to estimates from the International Monetary Fund of the price of austerity.

Christine Lagarde, the IMF's managing director, last week caused consternation among governments that have embarked on controversial spending cuts by arguing that the impact on economic growth may be greater than previously thought.

The independent Office for Budget Responsibility implicitly used a "fiscal multiplier" of 0.5 to estimate the impact of the coalition's tax rises and spending cuts on the economy. That meant each pound of cuts was expected to reduce economic output by 50p. However, after examining the records of many countries that have embraced austerity since the financial crisis, the IMF reckons the true multiplier is 0.9-1.7.

Wow, who could have predicted that? Well, everybody who isn't a conservative.

Neal Lawson, director of left-wing pressure group Compass, said, "the cuts were never going to work, but these calculations show the effect is bigger than anyone judged. The economy isn't suffering from government borrowing but a severe lack of demand that only the government can fix."

Osborne told reporters in Tokyo that the IMF does not allow for the boost provided to growth by the Bank of England's £375bn of quantitative easing. "The point I would make about their study of the fiscal multipliers is that they explicitly say they were not taking into account offsetting monetary policy action. In the UK, I would argue we have a tough and credible fiscal policy to allow for loose and accommodative monetary policy and I think that is the right combination."

But many economists believe the dent in growth caused by austerity policies may be larger than first thought, because the financial crisis has left banks starving firms and households of credit; and with many countries cutting back simultaneously, it is harder to fill the gap created by cuts with demand for exports.