Is Green the new red?

For the past hundred years or so, the Labour Party has been the main beneficiary on the left of the tactical voting that the UK’s first past the post system has rendered necessary. In the 2024 election especially, Labour was voted for overwhelmingly, less because of any love for them, and more because of a dislike of the main right wing party, the Conservatives. However, recent developments have seen a threat to Labour’s position as the main left wing party; the increasingly rightwards shift seen under Keir Starmer, coupled with the meteoric rise of the popularity of the Green Party, have made the impression that the Greens are now the main party of the left.

The perfect case study of this is the ongoing by-election in Gorton and Denton, which has seen a brutal three way between Labour, the Greens and Reform threaten to give Reform UK the win in a crucial electoral contest. Labour’s main talking point for the entire election has been the threat of Reform winning, but multiple new polls, including data from both Green and Reform campaigners, have shown that the Greens are leading not just over Labour, but over their teal adversaries as well. Based on this, it looks as though if Labour are not to be hypocrites, they themselves must drop out of the Gorton and Denton race; the Greens are clearly the leading left wing party, and if Labour are to stick to their informal policy of “anyone but Reform”, their best chance is to surrender Gorton and Denton to the Greens.

While this will not be a huge upset in terms of actual political power - Labour have more than 400 MPs, they can afford to lose one - it would represent a profound psychological shift. For more than a century, the gravitational pull of the British left has centred on a single axis: the Labour Party. Even during periods of schism, from the formation of the SDP in the 1980s to the Corbyn-era civil wars of the 2010s, the assumption has remained that Labour is the vehicle of government, and all other progressive forces orbit around it.

The suggestion that the Green Party could supplant Labour as the primary standard-bearer of the left would once have seemed fanciful. For decades, the Greens were treated as a pressure group with ballot access - principled, persistent, but peripheral. Their electoral successes were sporadic and localised, often strongest in university towns and affluent urban enclaves. Even their breakthrough parliamentary win in 2010 was framed as a curiosity rather than a harbinger.

Yet politics has a habit of accelerating in unexpected directions. Under Keir Starmer, Labour has pursued an unapologetically cautious path. The leadership has prioritised fiscal restraint, party discipline and a deliberate distancing from the more expansive spending pledges of previous manifestos. To supporters, this has restored credibility and electability. To critics, it has hollowed out ideological distinction, leaving a party managerial rather than transformative.It is within this perceived vacuum that the Greens have flourished. Their messaging has broadened beyond environmentalism to encompass rent controls, public ownership of utilities, wealth taxes and proportional representation. In local elections, they have demonstrated an ability to convert protest sentiment into council seats. Their activists, often younger and digitally savvy, have built visible ground campaigns in areas long assumed to be safely Labour.

Gorton and Denton - a constituency that would historically have been described as rock-solid Labour territory - has therefore become symbolically potent. The presence of Reform complicates the arithmetic. Reform’s appeal, rooted in anti-establishment rhetoric and hardline positions on immigration and culture-war issues, has fragmented the right-wing vote while also attracting disillusioned former Conservatives. In a straight Labour-versus-Reform fight, tactical voting might once have been straightforward. But with the Greens polling strongly, the calculus changes.Labour’s argument has been blunt: a split in the progressive vote risks allowing Reform to “come up the middle.” The appeal is familiar. For decades, Labour has benefited from the logic of first past the post - voters lending their support not out of passion but pragmatism. The Greens, however, have turned that argument back on Labour. If the overriding objective is to block Reform, they contend, then voters - and indeed parties - should back whichever candidate is demonstrably best placed to do so.

This is where accusations of hypocrisy arise. Labour figures frequently advocate tactical coordination when it benefits them, quietly welcoming stand-down arrangements from smaller parties in marginal seats. But they stop short of endorsing formal pacts or reciprocating. To stand aside in Gorton and Denton would be unprecedented in modern times: an admission that Labour is not the dominant force on the left in that constituency. The national implications would reverberate far beyond a single by-election. 

British politics has long operated on an implicit binary: Labour versus Conservative, red versus blue. Even as the Conservatives regroup in opposition, the system remains structured around that duality. If green begins to replace red as the default progressive option in certain areas, it fractures that binary and introduces a new unpredictability.

It would also intensify pressure for electoral reform. The Greens have consistently championed proportional representation, arguing that first past the post distorts voter preferences and entrenches two-party dominance. Ironically, their potential breakthrough in Gorton and Denton depends precisely on that system’s quirks. A concentrated surge of support, even without majority backing, could be enough to secure victory. Should they achieve it, the case for reform would gain a compelling new exhibit: proof that voters are willing to realign when offered a viable alternative.

However, caution is warranted before declaring a wholesale realignment. By-elections are notoriously volatile. They attract protest votes, lower turnout and outsized media attention. Voters often use them to send messages rather than choose governments. Labour’s national infrastructure, financial resources and parliamentary dominance remain formidable. One seat - even symbolically resonant - does not erase a century of institutional entrenchment. Moreover, the Greens face structural challenges if they aspire to become a national party of government. Scaling up from pockets of concentrated support to a broad, cross-regional coalition requires policy trade-offs and message discipline. It also invites scrutiny. Labour’s rightward drift, as critics see it, has been partly a response to relentless attacks over economic credibility. Should the Greens approach similar levels of power, they would encounter comparable pressures.

Yet symbolism matters in politics. If Gorton and Denton were to fall to the Greens, it would signal that Labour’s hold over progressive voters is conditional rather than automatic. It would demonstrate that tactical voting can run in multiple directions. And it would embolden activists elsewhere to test whether similar conditions exist in their own constituencies.

For Starmer’s leadership, the lesson would be stark. Electoral dominance does not guarantee ideological loyalty. A party can win a landslide while leaving segments of its base feeling politically homeless. The question is whether Labour interprets a potential Green surge as a temporary protest to be weathered, or as a warning that its repositioning has opened space to its left.

For the Greens, the opportunity carries equal risk. To claim the mantle of the “main party of the left” is to invite expectations commensurate with that title. It demands not only principled policy platforms but also credible pathways to implementation. The transition from insurgent outsider to plausible governing force is fraught, as history shows.

Ultimately, the contest in Gorton and Denton may prove less about the arithmetic of one by-election and more about the psychology of alignment. If voters begin to believe that green can win where once only red could, behaviour shifts. Tactical instincts recalibrate. Donors reconsider. Activists relocate. Momentum, once ignited, can be self-reinforcing.Is green the new red? The answer is not yet clear. 

But for the first time in generations, the question does not feel rhetorical.