When Rachel Reeves’ Budget preparations descended into chaos earlier this month, after the Financial Times revealed that the chancellor had ripped up her plan to increase income tax, one cabinet minister conveyed the mood among Labour MPs with a single “horror” face emoji.

Reeves was furious, according to people close to her. Markets tumbled amid fears that Labour MPs, anxious about the political damage that would be incurred from such a blatant manifesto breach, were now writing the Budget, not the chancellor.

Reeves had spent weeks preparing Labour MPs, the markets and the country for a Budget on November 26 that would be so tough an election pledge not to raise income tax rates would have to be broken. The U-turn suggested that the chancellor had lost control.