Of all the world leaders at the Cop27 summit today, I suspect Rishi Sunak will be one of the least comfortable with the whole jamboree. How can he justify a £50 billion-a-year net zero programme without anyone having worked out what difference, if any, the proposed extra taxes and regulations would make? How can a PM jet off to a luxury Egyptian resort and pledge this kind of cash – then fly back to London and constrain NHS and school spending, slash aid money, hike taxes, impose deep real-terms cuts in public pay – all to plug a £35 billion...