A dramatic victory in a parliamentary special election. Hundreds of seats won in English municipalities. A first taste of power in the lower tiers of government.

By making extensive gains in a set of local elections held in England on Thursday, Nigel Farage, one of Britain’s best known supporters of President Trump and the leader of the anti-immigration Reform U.K. party, consolidated his reputation as the country’s foremost political disrupter.

But he may have done something bigger still: blown a hole in the country’s two-party political system.

For nearly all of the past century, power in Britain has alternated between the governing Labour Party, now led by Prime Minister Keir Starmer, and the opposition Conservatives, who last year selected a new leader, Kemi Badenoch.

Yet with surging support for Reform and gains for other small parties, that duopoly has rarely looked more shaky.

“The two main parties have been served notice of a potential eviction from their 100-year tenures of Downing Street,” said Robert Ford, a professor of political science at the University of Manchester.