@TheNuthatch
It all makes more sense now…
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.
Ahead of Wednesday's Budget, is the OBR really the tail wagging the Treasury dog?
Lou Haigh, a former Labour Cabinet minister, has called the OBR an "unelected institution dictating the limits of government ambition". And just last week the Trades Union Congress accused the "unaccountable OBR" of being a "straitjacket on growth".
So, ahead of Wednesday's Budget, is the OBR really the tail wagging the Treasury dog - and if so, could this partly be at Labour's own hand for having changed the department's role in the first place?
At the end of October, one month before the Budget, the OBR is understood to have lowered its forecast for productivity - a measure of the output of the economy per hour worked - by 0.3 percentage points. Productivity plays a key role in long-term growth prospects and therefore can influence Budget decisions.
According to the Institute for Fiscal Studies think tank, for every 0.1 percentage point downgrade in the productivity forecast, government borrowing would increase by £7bn in 2029-30 - meaning a 0.3 point cut could add £21bn to Rachel Reeves's Budget black hole.
BBC