Dominic Cummings’ survival prospects as the prime minister’s most senior adviser have been dealt a major blow by Steve Baker. Throughout Saturday, Downing Street insisted that Cummings continued to enjoy the prime minister’s confidence. But on Sunday morning Baker, the MP for Wycombe, broke cover to become the first Conservative MP to publicly call for Cummings to be sacked.

What makes Baker’s intervention so damaging is his long association with Cummings in the Vote Leave campaign. In January 2016 when the Board of Vote Leave attempted to remove Cummings as campaign organiser, Baker was among those who helped defuse the situation. But relations deteriorated when Cummings subsequently accepted Theresa May’s withdrawal agreement. The proposed legislation was blocked by Conservative MPs marshalled by Baker’s “Spartan” faction within the European Research Group.

Writing in The Critic, Baker makes clear that his call for Cummings’ dismissal goes deeper than the charge that he “clearly broke” the guidelines on keeping parents at home to prevent travel during lockdown. Baker states that he has “always opposed Dominic being in Number 10” because of his “disdain for accountability.” As Downing Street chief of staff, his misjudgements and attitude have, Baker writes, burned “Boris’s capital when it is most needed.”

Baker calls for wider reforms to prevent what he regards as the narrow advice and poor software coding that informed the government’s coronavirus strategy, but it is his attack on Cummings that will have the most immediate sting.

As a well-respected MP, Baker’s intervention alerts Downing Street that Cummings is losing support even from the pro-Brexit wing of the parliamentary party who have wearied of his role and influence in government. With unease within the cabinet and the backbench at the refusal of Cummings to resign of his own accord, Baker has provided the covering fire for other prominent members of the Conservative party to also call for the prime minister to be rid of his turbulent adviser.