Mr Rees-Mogg’s broadside against the Office for Budget Responsibility was greeted with disbelief by economists, with one saying his input was vital to the credibility of any statements by Chancellor Kwasi Kwarteng. And today, Liz Truss’ official spokesman said the Prime Minister has full confidence in the OBR’s ability to make accurate forecasts. The spokesman also said the IMF – which came in for another tongue-lashing from Mr Rees-Mogg – played an “important role”, which Mr Kwarteng appreciated. The Business Secretary’s highly unusual criticism of the independent budget watchdog came just days after the OBR presented its initial estimate of the impact of the chancellor’s September 23 mini-budget to the Treasury. His comments prompted speculation that the findings are damning and that there is an attempt to undermine faith in them ahead of their final verdict on October 31. Speaking on ITV’s Peston show on Wednesday, Mr Rees-Mogg said the OBR’s “record of forecast accuracy was not exceptionally good”. He added: “The chancellors’ job is to make decisions in the round rather than assuming there is some single forecaster who will hit the nail on the head. “There are other sources of information. The OBR is not the only organization that can provide forecasts.’ However, when asked on Thursday whether Ms Truss had confidence in the OBR’s ability to provide accurate forecasts, the prime minister’s official spokesman said: “Yes.” They said: “The OBR is the Government’s official forecaster and the Prime Minister has said on many occasions that she values ​​their scrutiny and respects their independence. It is a body that is highly respected worldwide.” Asked what alternative forecasts were available, the official said: “It is true that other forecasts are being made and it is important that all available evidence and views are taken into account when making these kinds of important decisions, but the OBR remains the Government’s official forecaster.” . Pressed on whether it was helpful for Mr Rees-Mogg to belittle the OBR, they said: “The OBR are very transparent and recognize that these are the challenges when you’re making forecasts yourself. However, their work is highly regarded worldwide.” Paul Johnson, director of the Institute for Fiscal Studies, said it was clear that economists could never be completely accurate in their predictions about the future. But he said that, contrary to Mr Rees-Mogg’s insinuations, the OBR had previously had a track record of painting an overly rosy picture of the economy, rather than an overly bleak one. “The OBR has historically been overly optimistic about the economy,” Mr Johnson said. “The economy has actually done worse than the OBR suggested.” He added: “Of course they matter. It is very important for credibility, which has become so important in recent weeks, that we have these official forecasts and the chancellor responds to that by saying: “This is how I see my fiscal policy”. Earlier on Thursday, Mr Rees-Mogg said the Office for National Statistics figures could not be relied upon and suggested the Bank of England may be to blame for the market panic that followed the chancellor’s mini-budget. His views were soon echoed by economic experts. Nigel Peaple, director of policy and advocacy at the Pensions and Lifetime Savings Association, said the market turmoil was “mostly caused by the mini-budget [and] uncertainty about the government’s plans”. Deutsche Bank’s UK chief economist Sanjay Raja said the mini-budget was the “straw that broke the camel’s back”. And Financial Times US editor-in-chief Gillian Tet hit back at Mr Rees-Mogg’s remarks, telling Channel 4 News: “To use a non-technical term, that’s pretty much a barrier.” The chief executive of the Resolution Foundation, Torsten Bell, said: “If you spend the summer telling people that you intend to abandon fiscal orthodoxy, if you then announce a package that rejects fiscal orthodoxy, then if you say on Sunday that you will continue to do, then I don’t think it should come as a surprise to any of us that this is where you end up.”