Britain’s populist, anti-immigration party Reform UK has beaten Labour by a tiny margin in a by-election, dealing the government a mid-term setback and ruffling the country’s historically resilient two-party hegemony.

The hard-right party Reform UK led by Nigel Farage won a seat in Parliament by a handful of votes and looked set to make more gains in results Friday from local elections the party hopes will show it is a major player in British politics.