Hannah Spencer’s win in the Gorton and Denton parliamentary byelection was a momentous victory for the Green party. The party’s first-ever byelection win overturned a large Labour majority and put the general election winners into third place, behind Reform UK.
The Greens are eager to position it as a sign of things to come, particularly in the May elections. Here’s what voter trends in Gorton and Denton can tell us about what’s to come.
Voters continue to turn away from the two main parties
Voters are looking for alternatives to the two main parties. Labour’s vote share halved in Gorton and Denton compared to the general election. With a much smaller 2024 base to start from, the Conservatives went from nearly 8% of votes to fewer than 2%, losing their deposit.
This follows a trend we’re seeing at almost every election, regardless of type or location. In the 2025 local elections, fewer than 40% of incumbents from the two main parties held their seats – a figure that had previously never been below 70%. In council byelections, both Reform and the Greens are fielding candidates in more areas, and taking both vote share and seats from the Conservatives and Labour. Labour and the Conservatives are the only two parties with fewer MPs than they started this parliament with.
Voters deciding late
Constituency opinion polls in the run-up to byelection day showed Labour, Reform and the Greens neck and neck.
But a more striking feature of these polls was how many voters had not yet made up their minds. Even in the final week, an Omnisis poll found that 31% of people who said they would vote were still undecided, more than the reported support for Labour (18%), the Greens (22%) or Reform (20%).
This is an unusually high level of uncertainty so late in a campaign. In normal elections, the rate of undecided voters is typically lower by the eve of polling day. Here, nearly a third of voters were still making up their minds. This compares to 12% two days before the general election, which was itself considered high.
Late-deciding women may have swayed the outcome
High numbers of undecideds may partially explain the late swing to the Greens. We know that women are more likely than men to respond “don’t know” to vote intention questions and to decide later in the campaign. At the same time, there is a gender gap in party support: Reform performs better among men, while the Greens tend to perform better among women, particularly among younger voters.
Levels of undecidedness between men and women differed, with 18% of men reporting they were undecided relative to 36% of women in the Omnisis poll. There were also more men than women, by ten percentage points, saying they would not vote. If those undecided women were less inclined to support Reform and more open to supporting the Greens, then late-deciding voters may well have tipped the balance.
Adam Edwards/Alamy
Undecided women are less likely to think that any party represents their policy priorities well. This is particularly unlikely to have played out well for Reform – the party has expressed support for taxing women without children more and repealing the Equality Act.
This contest is a reminder that women voters may prove decisive when large numbers of people are still making up their minds. With the next general election still some way off, and current levels of undecidedness in the electorate high, this is something parties would do well to keep in mind.
Turnout doesn’t always fall
This byelection was the second in the past six months where voters have turned out in higher-than-expected numbers. The Caerphilly Senedd byelection in October 2025 also saw unusually high turnout of 50.4%, a 6.1 point increase on the 2021 Senedd election.
Ahead of election day in Caerphilly, polls had Reform on 42% (up from 1.7% in 2021), Plaid Cymru on 38% (up from 28.4%), and Labour on 12% (down from 46% in 2021). On election day itself, Plaid took the seat from Labour with 47.4% of the vote, to Reform’s 36%, with Labour falling to third place on 11% of the vote.
In Gorton and Denton, the 2024 general election turnout was the 32nd-lowest across the country, at just 47.8% But it fell only 0.3% at this byelection. Taken together, these two contests suggest we may be seeing the beginnings of an electoral trend.
In both cases, voters opted for a party positioned to Labour’s left as the most credible option for stopping Reform. With Reform’s overwhelming success in the local elections in England last year and continued strong headline polling figures, it is possible that we are beginning to see an anti-Reform mobilisation effect. Rather than staying home, voters on the left may be turning out in greater numbers than we would otherwise expect, to back whichever party is best placed locally to prevent a Reform win.
À lire aussi :
Tactical voting: why is it such a big part of British elections?
What does this mean for the future?
The Labour government has responded to their decline in national opinion polls by positioning themselves against Reform in key areas such as immigration. Yet, with evidence that British politics is developing left v right bloc-style voting, Labour might be unwise to ignore the threat from its own side of the ideological spectrum.
We already saw early signs of this in the 2024 general election itself, when some of Labour’s largest drops in support came in progressive, urban constituencies where the Greens also increased their support.
Some in the party have already taken this lesson from Gorton and Denton, while others, including the prime minister, are counting on the Greens not having the same campaigning resources for general elections.
If women who are answering “don’t know” to polls follow the Gorton and Denton trend, they may be leaning more towards Green than the headline vote intention figures suggest. This should be ringing alarm bells for Labour. The Greens came second in 40 seats at the 2024 general election – all of those were seats Labour won.
Moreover, if Reform are motivating both their supporters and their opposition to the polls, the Greens may be rising as Labour’s alternative on the Left. This was one seat with its own context, so it’s difficult to apply nationally. But we could see a scenario in May where both Reform and the Greens combined overtake the Conservatives and Labour.
You must be logged in to post a comment Login