Sir Keir Starmer was anxious. It was early June 2024, and the leader of the Labour party was being urged by campaign strategists to make an election promise that would come back to haunt him: a vow that he would not put up any of Britain’s main taxes. “Keir was nervous,” recalls one ally. “Everyone was nervous. We definitely knew it was risky.”

Starmer’s promise helped him win power, but after little more than a year in office it is set to be broken. Barring a last-minute change of heart, Starmer’s chancellor, Rachel Reeves, will this month renege on the vow to the British public and put up income tax in her Budget on November 26. Such a strategy is deemed so perilous that it has its own place in political folklore: the dreaded “read my lips” moment.

This refers to a steamy night in the New Orleans Superdome in August 1988, when then presidential candidate George HW Bush made perhaps the most famous broken pledge in politics when he told the Republican convention: “Read my lips: no new taxes.” Once he was in the White House, taxes did indeed go up, and the phrase dogged him in his second, unsuccessful campaign for president four years later. The question of “trust” became a central election issue.