Within seconds of Sajid Javid’s shock resignation, MPs and Whitehall watchers were pointing the finger at Boris Johnson’s senior aide Dominic Cummings.
The notoriously abrasive special adviser, who earlier this week appeared to suggest a team of cartoon superheroes called PJ Masks could do a better job than the then Cabinet, sometimes appears to relish confrontation, whether it is with senior politicians, civil servants or journalists.
He has made no secret of his determination to shake things up in the corridors of power and has shown no sign of any concern about what enemies he makes along the way.
Born in Durham and educated at Oxford University, he makes much of his northern roots though he is married to the daughter of an aristocrat.
He rose to notoriety in politics first as an adviser to Michael Gove and then as campaign director at the official Brexit referendum campaign group.
Many will know him as the character played by Benedict Cumberbatch in the HBO/Channel 4 comedy-drama film Brexit, and for as his role in covering a red bus with the notorious £350 million NHS claim.
The campaign group was also fined £61,000 for breaking the rules in the build-up to the vote.
Cummings is variously seen as a genius, a maverick, or a troublemaker.
He was once also labelled a “career psychopath” by former prime minister David Cameron.
But Mr Cummings is not shy of firing off an insult himself.
In 2017, he described David Davis, then the Brexit secretary, as “thick as mince, lazy as a toad and vain as Narcissus”.
Mr Johnson appointed Mr Cummings to his top team as senior adviser at Number 10 when he became Prime Minister in the summer of 2019.
The appointment was controversial, given that he was found to be in contempt of Parliament earlier in the year for refusing to give evidence to MPs investigating misinformation.
But Mr Cummings appears to enjoy controversy, deliberating cultivating a reputation as someone who does not play by the rules of conventional politics.
He infuriated Mr Javid by sacking one of the then chancellor’s aides Sonia Khan in what was seen by many in Whitehall as a particularly brutal manner, having her escorted from Downing Street by police.
He appeared impervious to the flak he received as a result, having apparently blamed her for the leaking of a Treasury report on the risks from Brexit.
And the controversy did nothing to temper his confrontational approach.
Soon afterwards, when told by Labour MP Karl Turner that the PM’s use of words like ‘surrender’ had led to death threats being levelled at parliamentarians over the Brexit impasse, Mr Cummings simply replied: “Back a deal, then.”
He continued the “people versus Parliament” rhetoric by saying the fury of some voters was unsurprising.
Mr Johnson’s decisive victory in the December 2019 election if anything emboldened Mr Cummings, who appears scornful of the Whitehall convention that special advisers should remain in the shadows.
He soon set to work on his goal of reshaping Whitehall, issuing a recruitment call for “weirdos and misfits with odd skills” to shake up the Civil Service.
Now he has well and truly shaken up his boss’s reshuffle.
What is not yet clear is whether this was part of his plan.