Dominic Cummings was no stranger to controversy even before Boris Johnson hired him as his senior aide in Downing Street.
He rose to prominence in politics first as an adviser to Michael Gove and then as campaign director at the official Brexit group Vote Leave.
His role in the stunning victory for that campaign made him a hero to many Brexiteers but a hate figure for some Remainers.
His public profile was boosted when he was later portrayed by Benedict Cumberbatch in a Channel 4 drama about the campaign, which played up his role in covering a red bus with the hotly-disputed £350 million-a-week for the NHS claim.
Mr Johnson hired Mr Cummings as senior adviser at Number 10 when he became Prime Minister in the summer of 2019.
The appointment of the abrasive former campaign director was controversial especially given he had been found to be in contempt of Parliament earlier in the year for refusing to give evidence to MPs investigating misinformation.
But Mr Cummings has built a reputation as someone who does not play by the rules of conventional politics.
He was once called a “career psychopath” by former prime minister David Cameron, according to widely reported remarks.
And he can dish out the insults himself, describing David Davis, then the Brexit secretary, as “thick as mince, lazy as a toad and vain as Narcissus” in July 2017.
The December 2019 election victory gave Mr Johnson the political capital he needed to take bold decisions – and Mr Cummings soon set to work on his goal of reshaping Whitehall, issuing a recruitment call for data scientists, economists and “weirdos and misfits with odd skills” to shake up the Civil Service.
In April, he was back in the headlines when it emerged he had been present at meetings of the official Scientific Advisory Group for Emergencies co-ordinating the Government’s response to the coronavirus pandemic.
Downing Street insisted there was nothing untoward about his attendance, but opposition MPs and some scientists suggested it risked political interference in science-based advice from Sage.
Mr Cummings also drew criticism when he returned to work after his own brush with Covid-19 and was pictured allegedly failing to follow the two-metre social distancing rules as he walked along Downing Street flanked by fellow aide Cleo Watson on April 14.