Dominic Cummings, picked last week by British Prime Minister Boris Johnson to be his top adviser, is a combative and unorthodox political strategist credited with masterminding the unexpected 2016 Brexit vote victory.
The director of the official Leave campaign, Mr Cummings is hailed as an innovative disruptor who will bring his win-at-all-costs mentality to delivering Brexit-alongside an instinct for radical reform of government.
Portrayed by actor Benedict Cumberbatch as a tortured genius in a TV drama this year about the EU referendum, the 47-year-old is not your typical political aide.
Famously described by ex-prime minister David Cameron as a "career psychopath", Mr Cummings is a divisive figure within British conservative circles who has made a host of enemies with his acid-tongued approach to political debate.
He has been compared to Steve Bannon, US President Donald Trump's former chief strategist, and is similarly a keen student of military theories and tactics.
Mr Cummings' elevation, like Mr Bannon's, is seen as a risky move, with some sceptical that his uncompromising and caustic style can succeed at the heart of British government.
"Dominic Cummings is the disruptor's disruptor, he's strategically single-minded and ideologically iconoclastic," said Tim Bale, politics professor at Queen Mary University of London, who featured him in his 2011 tome "The Conservative Party: from Thatcher to Cameron".
"Civil servants and party apparatchiks may well have their noses put out of joint by his adviser, but for Johnson that's a price well worth paying if he can hang on to (power) and get us out of the EU."
Opposition parties have decried Mr Cummings' appointment, noting that he was found in contempt of parliament in March for refusing to appear before a committee probing fake news during the referendum campaign.
In trademark style, he dismissively accused its members of having "greater interest in grandstanding than truth-seeking".
On a personal blog where he posts everything from political musings to lengthy treatises, Mr Cummings argued last month that Britain's current Brexit-fuelled political dysfunction was "a once in 50- or 100-year crisis" to be exploited.
"Such crises also are the waves that can be ridden to change things normally unchangeable," Mr Cummings wrote.
'Us against them'
Born in Durham, northern England, to a father who worked as an oil rig project manager and a mother who was a special needs teacher, Mr Cummings attended a local private school before winning admission to Oxford University.
A Russophile with a passion for Dostoyevsky, Mr Cummings reportedly headed to the country after graduation and helped set up an airline in the 1990s, which however failed to get off the ground.
After returning to Britain, he first cut his teeth in politics by spearheading several campaigns, including against Britain adopting the euro.
In an early sign of his take-no-prisoners approach, Mr Cummings was made Conservative Party director of strategy in 2002, but left the role after eight months, branding then party leader Iain Duncan Smith "incompetent".
He became special adviser to education minister Michael Gove, later a leading Brexiteer, making a name for himself by developing an "us against them" bunker mentality within the department towards the rest of government.
He is said to disdain Britain's apolitical civil service, viewing it as a block on innovation.
'Wild and unpredictable ride'
After a period in the political wilderness, Mr Cummings was picked to lead the Brexit referendum campaign.
The victory crowned his reputation as a political maverick who could deliver against the odds.
The data-driven campaign used social media nimbly and was seen as reaching voters typically ignored by Britain's main parties, something that could soon come in useful for Mr Johnson as the likelihood of snap elections grows.
An admirer of 19th-century Prussian statesman Otto von Bismarck and US fighter pilot and military strategist John Boyd, Mr Cummings appears already to be deploying the latter's core philosophy of trying to confuse opponents by defying expectations.
Mr Johnson undertook an unexpectedly brutal cabinet reshuffle last week, while on Brexit he has surprised observers by making no immediate plans to travel to European capitals, insisting that Brussels must compromise first.
Dominic Cummings' fingerprints are seen as all over the tactics.
Notably, he is pictured in the background of photos of Johnson entering Downing Street last week, standing out from other suited civil servants in jeans and a T-shirt.
Damian McBride, a former adviser to Labour prime minister Gordon Brown, said of Mr Cummings' early manoeuvres: "It all suggests a wild and unpredictable ride ahead."