It is the proposal that a British prime Minister should be dying in a ditch to kill off given that the City generates about a tenth of Britain’s economic wealth. The kind of proposal that might be aired by a Frenchman, purely to outrage Britain. It is, of course, a trick: Brown knows it won’t be agreed because it requires the approval of every major currency-trading country – and that will never be secured. It has been explicitly rejected by the Americans, which was perhaps the intention. But everyone else at the G20 will see Brown’s proposal for what it is: the desperate vote-seeking move of a Prime Minister who knows he’s going down.