So, Dominic Cummings is to leave No 10 at Christmas and would have us believe that it was always the plan. I am not so sure. Having witnessed a few from very close quarters, I know a Downing Street power struggle when I see one.

Boris Johnson has relied heavily on Cummings and, having gained his life’s ambition to become Prime Minister, was determined to hold on to the prize and brought Cummings, the architect of the Vote Leave campaign, into the heart of government. Indeed it was made plain that “Team Leave” was running the country with the two primary objectives to leave the EU with a negotiated exit and to win a general election so that the negotiated exit could be ratified by Parliament.

And that is where the trouble started. For Cummings his small team in No 10 and carefully positioned as advisers in key government departments, Brexit was all they were ever really after. They were quite prepared to breach the constitution (yes we do have one, just not one written in a single document), alienate members of the Conservative Party, attack the Civil Service and Judiciary, and undermine the media, to get Brexit done.

And then it was done. Johnson secured a very healthy Parliamentary majority last December, we left the EU on 31 January. Rather than hang up his boots and declare the game over, Cummings did not walk away; he turned his attention to reform the very nature of Government. At the beginning of this year in a now notorious blog he called for “misfits and weirdos” to come help him tackle “some profound problems at the core of how the British state makes decisions”  with the freedom brought by “a new government with a significant majority and little need to worry about short-term unpopularity while trying to make rapid progress with long-term problems.” No one could accuse the man of lacking ambition.

But he has been thwarted by the virus. While he wanted to focus on the big picture, the response to the outbreak has demanded attention to the detail. Whether it was test and trace, exams, school meals, the timing of the second national lockdown, the government has been found wanting and the Prime Minister’s own authority has been called into question by his own backbenchers, many of whom are still furious about Cummings’ personal behaviour.

It was time for around Johnson whose weren’t part of Team Leave to turn up the pressure on him to get a grip, including by appointing a chief of staff, something Cummings had thus far persuaded him he could do without. Imagine the dismay when Johnson revealed he was appointing Lee Cain, one of Cummings’ closest allies, to the role. No wonder they told him very firmly “no”. And the Prime Minister listened.

Recognising his star was in the decline, Cummings has decided to jump before he was pushed. He might want us to think it was always his intention. He points to that infamous blog in which he says he wants to be redundant within a year. But of course, his work hasn’t been done. It wasn’t really started. Perhaps he believes that a role much further behind the scenes is what will help get it done.

The shape and extent of Johnson’s legacy will very much depend on his ability to resist the temptations of Cummings no matter how far off stage he is.