The difficult question about how powerful the Budget watchdog is

Faisal IslamEconomics editorBBCBudget days used to be symbolised by the chancellor of the exchequer smiling and holding aloft the famous Red Box outside Number 11. Inside is a red book that contains the measures to be read out in the Budget speech.These days, however, it's a blue book that's in the spotlight. Or more precisely, a chunky chart-filled analysis of the Budget, assessing the cost of government…