Budget 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 policies, published by a team that sits in a far corner of the Ministry of Justice building - one that few people outside this closed world know much about.
Yet it's also a department that has extraordinary influence over economic policy.
Now a debate is bubbling about whether this small department, known as the Office for Budget Responsibility (OBR) - and staffed mainly by young intellectuals and civil servants - is in fact too powerful, with claims from some that it is essentially half-running the government economic policy.
And indeed whether its chairman, Richard Hughes, a Harvard-educated former Treasury mandarin, has in fact become as important as the real chancellor.
