On February 26, the United Kingdom held a special parliamentary election in the Gorton & Denton district, which is in Manchester. Previously, the Labour Party had won this district in every election starting in 1931. However, the Green Party won. Eleven candidates were on the ballot. The Green, Hannah Soencer, won with 41%. See this wikipedia article about the election. This was only the second special Parliamentary election in the United Kingdom since the general election of 2024.
The only other constituency in the United Kingdom that had ever elected someone who was solely a Green Party nominee had been Brighton. That district elected Caroline Lucas in 2010 and re-elected her in 2015, 2017, and 2019. She did not run for re-election in 2024.