The striking thing about the result of the Gorton and Denton by-election is how confidently voters broke from their old pattern. Instead of rallying behind Labour to keep Reform out, they shifted to the Greens who went on to win. It overturns the story Labour has been telling over and over, and it raises real questions about how voters will behave in May.

The result is pretty historic in its own terms. It’s the Greens first parliamentary by-election win and it happened in an area where Labour had not been beaten since 1931. The idea that the Greens struggle to gain ground in the north has long underpinned Labour’s national confidence as the only credible ‘left’ alternative, but that no longer holds. A Manchester seat choosing the Greens ahead of both Labour and Reform shows the party can reach further than many had anticipated, and can now draw support from voters who once saw Labour as their only option.

The result also blows up one of Labour’s core messages. Locally, the party leant heavily on the idea that only Labour could stop Reform. Voters were told that a vote anywhere else would be a waste and simply help Nigel Farage’s party edge further into Westminster politics. Instead, Reform surged into second and the Greens showed that another anti-Reform option exists. Green leader Zack Polanski is already framing the win exactly that way, arguing that ex-Labour voters can now see his party as the best route to defeat Reform.

The result will sit in the minds of voters heading into the May elections. In places where Labour faces pressure from Reform, some will now see Gorton and Denton as proof that voting Green does not hand seats to Reform. With the Greens growing their local base and expanding their councillor numbers, they have the organisation to convert that shift into real gains. We are already seeing northern Green groups pick up that message with local factions in areas like Bradford, Wakefield and Trafford all pointing to Gorton and Denton as evidence that they can break through in May. It offers a practical case study for voters who want to move away from Labour without strengthening Reform.

This by-election points to a shift that Labour will find hard to ignore. With over 5,000 seats up for grabs in May, any repeat of this behaviour could reshape party control for councils across the country, and not just towards Reform as many commentators are expecting.