‘Brexit Brain’ Cummings to Leave Downing Street By Christmas

Number 10 special advisor Dominic Cummings leaves his residence in London on November 13, 2020. - British Prime Minister Boris Johnson's chief adviser Dominic Cummings is set to leave his position by early 2021, as a power struggle at the heart of government became public this week. Daniel Leal-Olivas/AFP via Getty Images

LONDON—Dominic Cummings, one of British Prime Minister Boris Johnson’s most powerful advisers, will leave his position at the heart of Downing Street when Brexit is done at year-end, after an internal battle over who should be Johnson’s chief of staff.

Cummings, who masterminded the 2016 Brexit referendum vote and the Tory party 2019 landslide election bid, told the BBC that his position had not changed since January when he said he wanted to be largely redundant by the end of this year.