LONDON — Dominic Cummings, the influential strategist who masterminded the Brexit campaign in 2016 and helped vault Boris Johnson to No. 10 Downing St., abruptly quit as his chief adviser on Friday, after days of fierce infighting over the role of hard-line Brexiteers who surround the prime minister.
Cummings left “with immediate effect,” according to the BBC, which had reported earlier that he would stay on until Christmas. The trigger for his departure was the resignation of his close ally, Lee Cain, who had been Johnson’s communications adviser and left after a squabble over the appointment of a new press spokeswoman.
A combative, mercurial figure, Cummings, 48, set out to overhaul Britain’s government bureaucracy under Johnson, amassing more power than any unelected political adviser in recent memory. He also shaped an ambitious program that sought to “level up” the economic disparities between Britain’s north and south.
But Cummings alienated many officials and politicians, who said his uncompromising style poisoned the prime minister’s relations with members of his Conservative Party in Parliament and hurt Johnson’s popularity with the public.
His departure, analysts said, could usher in a more conciliatory tone in Downing Street, which could even affect Johnson’s post-Brexit trade negotiations with the European Union, which are in a critical phase. But it will add to the perception that Johnson’s government is in disarray.
Allies of Johnson’s yearn for him to return to the more easygoing persona he had as mayor of London, rather than the crusading Brexiteer that he has sometimes seemed to be under the sway of Cummings.
“I’m not surprised in a way that it is ending in the way it is,” Bernard Jenkins, a Conservative member of Parliament, told the BBC. “No prime minister can afford a single adviser to become a running story, dominating his government’s communications and crowding out the proper messages the government wants to convey.”
Cummings’ reputation was tarnished in May after reports that he breached coronavirus lockdown restrictions by driving 260 miles to visit his parents in the northern city of Durham while he was falling ill with COVID-19. He visited nearby Barnard Castle, claiming that he was testing his eyesight before driving back to London.
“I don’t regret what I did; I think what I did was reasonable in these circumstances,” an unrepentant Cummings told reporters at the time.
Despite thunderous calls for his ouster, Johnson stuck by his adviser, attesting to his enormous influence over the prime minister’s political strategy and legislative agenda.
On Friday evening, Cummings was photographed leaving the building, carrying a box, as though he had cleared out his desk. The prime minister’s office did not confirm his departure.
The palace intrigue in Downing Street pitted Cummings and Cain, hardened veterans of the Vote Leave campaign, against the new spokeswoman, Allegra Stratton, a journalist whom Johnson recruited to deliver White House-style televised press briefings, and Carrie Symonds, a former Conservative Party communications adviser who is Johnson’s fiancée.
Cain objected to the role Stratton was carving out over communications strategy, according to media reports, and when Johnson offered to elevate him to chief of staff, Symonds questioned his suitability.
Cummings is known for his iconoclastic style. In a blog post in January, he complained that the civil service had too many “Oxbridge English graduates who chat about Lacan at dinner parties with TV producers and spread fake news about fake news.” Cummings himself studied ancient and modern history at Oxford.
After he helped engineer Johnson’s landslide victory in the election in December, Cummings posted a recruiting call for data analysts, software developers and economists to work as political advisers and “maybe as officials.” He said he was looking for “weirdos and misfits.”
It was the culmination of an unorthodox two-decade career for a political strategist and confirmed Euroskeptic who never joined the Conservative Party but made waves wherever he went.
In the early 2000s, Cummings worked as an aide to the former Conservative Party leader, Iain Duncan Smith. It did not go well. After quitting, he described his former boss as “incompetent,” adding that Duncan Smith would make a worse prime minister than the incumbent, Tony Blair.
When the Conservatives formed a coalition with the centrist Liberal Democrats in 2010, Cummings became a special adviser to Michael Gove at the education department. He waged war on an educational establishment that he nicknamed “the blob.” His reputation as an infighter became so notorious that the former prime minister, David Cameron, described him as a “career psychopath.”
In 2016, he turned his blend of populist instincts and ruthless campaigning skills to Vote Leave, the official Brexit campaign. His willingness to bend — sometimes distort — the truth appalled his opponents but even some of them admired the effectiveness of his slogan: “Vote leave, take back control.”
In a TV drama about the referendum, “The Uncivil War,” Cummings was played by actor Benedict Cumberbatch. On screen, he came across as a charismatic, if tortured, figure, determined to shake up Britain’s hidebound elite.