Against expectations, George Osborne announced in his Autumn Statement that borrowing would fall, not rise, this year. The news cheered the Conservative backbenches and clearly surprised Ed Balls, who was jeered by Osborne and David Cameron as he mistakenly said the deficit was "not rising" (he meant to say it was rising). Borrowing so far this year is £5bn (7.4 per cent) higher than in the same period last year - it seemed there was no escape route for the Chancellor.

So how did he do it? Well, turn to p. 12 of the Office for Budget Responsibility document and it becomes clear that Osborne has performed an accounting trick worthy of Enron. First, he added the expected £3.5bn receipts from the 4G mobile spectrum auction - even though it's yet to take place. Second, he included the interest transferred to the Treasury from the Bank of England's Quantitative Easing programme (worth £11.5bn), despite the Institute for Fiscal Studies warning him that it would call into doubt his credibility. Were it not for these two measures, borrowing would be £15bn higher than stated by Osborne. If we add that £15bn to the £108bn figure provided by Osborne, then total forecast borrowing for this year becomes £123bn, £1.4bn higher than last year. Little wonder that the Chancellor was so keen to bag the 4G receipts early.

But while these fiscal somersaults might allow Osborne to claim he's reduced borrowing, what reputation he had for statistical transparency has been destroyed. In his speech to the Commons, the Chancellor boasted that "it is a measure of the constitutional achievement that it is taken for granted that our country’s forecast is now produced independently of the Treasury". That claims looks very questionable today.