
On the third floor of an unassuming office block in Bloomsbury lies one of the institutions most feared by chancellors. For decades, Westminster has looked to the Institute for Fiscal Studies (IFS) to cast the definitive judgement on tax and spending policies.
Shortly before Rachel Reeves’s first Budget I met Paul Johnson, the think tank’s amiably nerdish director. Behind him rows of economists worked in near-silence as they prepared for the occasion (fuelled by pizza and coffee, they remain in the office until at least midnight).