Dominic Cummings is one of the most divisive figures in modern British politics and his list of enemies now appears to include the Prime Minister.
Sources at No 10 have pointed the finger at him for leaking messages from Boris Johnson, claiming Mr Cummings is “bitter” following his exit from Downing Street last year.
But to his admirers, Mr Cummings is the maverick genius who overturned conventional wisdom to deliver one of the biggest political shocks in decades in the Brexit referendum.
He then spent 16 turbulent months as the power behind the throne in No 10 before falling from favour.
Even after leaving Downing Street last year, following a power struggle involving the Prime Minister’s fiancee Carrie Symonds, Mr Cummings continued to leave no doubt about his open hostility to parts of the British political system.
Appearing before MPs in March he claimed the Department of Health and Social Care was reduced to a “smoking ruin” when the coronavirus pandemic hit.
And he told MPs: “As the country emerges from lockdown there should be an urgent, very, very hard look by this building (Parliament) at what went wrong and why in 2020.”
One of the key lessons to come out of the crisis was the need to go to “extreme lengths to try to de-bureaucratise the normal system” – a key theme in his political philosophy.
It was the coronavirus crisis that thrust the man who spent most of his career operating behind the scenes into the spotlight, through his infamous trip to Barnard Castle in apparent breach of lockdown rules.
The visit, and his claim he simply wanted to test his eyesight after recovering from coronavirus, attracted such attention that police complained it was undermining their efforts to enforce the regulations.
But Mr Cummings was no stranger to controversy before his ill-fated drive in County Durham.
As a special adviser to Michael Gove in the coalition government, his propensity for engaging in political scraps, particularly with the Tories’ Liberal Democrat partners, caused David Cameron to describe him as a “career psychopath” and seek to bar him from Whitehall.
He was however to emerge as the former prime minister’s nemesis in the Brexit referendum of 2016, when he was appointed director of the official Vote Leave campaign.
It was a role later portrayed in Channel 4 drama Brexit: The Uncivil War, in which he was played by Benedict Cumberbatch.
From the off his tactics were controversial. He ordered the campaign bus to be emblazoned with the disputed claim that leaving the EU would save £350 million a week to spend on the NHS.
Critics complained that the figure failed to take into account the funding the UK received back from Brussels, but Mr Cummings was only too well aware that the controversy simply served to highlight the sums Britain was sending the EU.
He was credited with devising the “Take back control” slogan which was seen to capture the mood of disillusionment which helped drive the Brexit vote.
And he was responsible also for a final online advertising blitz highlighting a potential influx of immigrants from Turkey if Britain remained in the EU, even though there was no imminent prospect of the country joining the bloc.
He later wrote that if Mr Gove and Boris Johnson, who were fronting the campaign, had not “picked up the baseball bat marked ‘Turkey/NHS/£350 million’ with five weeks to go” the result could have gone the other way.
Through it all, Mr Cummings made no secret of his contempt for the senior Tories on the Vote Leave board, complaining they would prefer to spend weekends off with their girlfriends than the hard business of campaigning.
There was therefore consternation among many at Westminster when Mr Johnson became prime minister in July 2019 and chose Mr Cummings to head up his No 10 operation.
Whitehall was given an early taste of how he would operate when he fired Sonia Khan, a special adviser to then chancellor Sajid Javid, and had her marched out of Downing Street by an armed police officer for alleged leaks.
With Parliament deadlocked over Brexit, he was seen as the author of the plan to prorogue its sittings, subsequently ruled unlawful by the Supreme Court, and the purge of the One Nation Tories who refused to back Mr Johnson’s deal for leaving the EU.
When the Prime Minister finally secured the general election he craved, it was Mr Cummings who came up with another simple but brutally effective slogan – “Get Brexit done” – which helped propel him to an 80-seat majority.
With the Government’s position finally secure, Mr Cummings set about some of his pet projects, including an overhaul of the machinery of government, warning there was a “hard rain” coming for Whitehall.
A long-standing critic of what he regarded as the Oxbridge mentality which dominated the upper echelons of the civil service, he appealed for “weirdos and misfits with odd skills” to transform the way the country was run.
He was certainly happy to cultivate the image of himself as the outsider, turning up to work in Downing Street in ill-fitting jeans and scruffy jumpers rather than traditional suit and tie.