The revelation from HMRC that the extra cost to the economy of new technology controlled borders will be in the order of £20 billion annually comes as no surprise. Countries do not organise customs unions and free trade deals because they do not know what to do with their days; they set them up because the alternative is too expensive and reduces both living standards and trade. Downing Street’s response to the damning evidence given by the head of H.M. Revenue and Customs to the Treasury Select Committee, is that it knows there are problems. Wow. Clever.