You can already sense Rachel Reeves’s spin machine whirring into action. It was Donald Trump wot ruined my careful book-keeping, the Chancellor will tell us as once again her fiscal headroom disappears and she ends up banging her scalp painfully on the ceiling. But could it be unrealistic expectations for her welfare reforms which prove her undoing? Tucked away in the government’s own figures is the revelation that Labour’s welfare shake-up could result in 400,000 more people signed off unfit for any work.