‘Does it score?’ How the OBR became the key arbiter of the Treasury’s sums

Reeves has clung to her ‘non-negotiable’ fiscal rules, and promised not to repeat anything on the scale of last October’s tax-raising budget. Photograph: Yui Mok/Reuters

When Rachel Reeves made her speech as shadow chancellor to Labour’s annual party conference two years ago it was one of the more niche announcements that drew a cheer from the audience.

Strengthening the role of the Office for Budget Responsibility might have sounded like a dry measure to unveil to the party faithful. But, after the Liz Truss debacle, handing the Treasury watchdog more powers went down a storm in Liverpool.