The history of by-elections is littered with contests which seemed to indicate a sharp change in the direction of British politics, only for the old order to return at the following general election. Remember those SDP victories in the 1980s which were followed by Mrs Thatcher’s two biggest general election majorities?

Even so, there is something disturbing about the result of the Gorton and Denton byelection. It was yet one more sign of the growing religious sectarianism in British politics. The Greens won this seat because of their shameless targeting of Muslim voters who make up 28% of the population in the constituency. The party distributed leaflets in Urdu declaring that “Labour must be punished for Gaza”.

Its candidate, Hannah Spencer, posed outside mosques wearing a keffiyeh around her head – a symbol of Gaza resistance – and boasted of fasting for a day at the beginning of Ramadan. True, Keir Starmer shot Labour in the foot by excluding Andy Burnham, who would have very likely won, albeit on a reduced majority. Disillusioned Labour voters would have supported him because they would have seen his election as a way to speed up the removal of Keir Starmer.

Nor was this the ideal seat for Reform UK. Besides a heavy Muslim vote, there are a large number of students in the constituency, and the election was held during term time. Reform UK’s natural constituency, by contrast, is white working class voters in the upper age brackets.

Even so, the Green’s transition from being a party of climate protest to being one of solidarity with Gaza – a journey which has been followed by many climate activists, Greta Thunberg included – was surely pivotal. They picked up the votes which unseated Labour MPs in some Muslim areas even during the party’s 2024 landslide.

Some Greens appear to see their support for Gaza as a jolly jape which, in the words of one of their number, ‘triggers’ the Right. If only that were true. But their election communications seem to have been designed to trigger other ethnic minorities. One leaflet showed Starmer standing beside Narendra Modi, the Indian Prime Minister. Never mind the context – that the UK and India were signing a trade deal which could help enrich Britain – it was a brazen attempt to signal to the large number of voters of Pakistani heritage in the constituency that Starmer is somehow on the side of Pakistan’s deadly enemies, India.

The Greens’ electoral strategy, sadly, it’s likely to come at the cost of community relations between Britain’s Muslim and Hindu populations. The Gorton by-election marks the point at which Britain moved from being a three-party system to a four-party one. The Greens are now the mirror image of Reform UK: an insurgent party of the Left. Look at their dramatic rise under Zack Polanski and it’s not impossible to imagine them becoming the largest party after the next election, forming a coalition with Labour and the LibDems.

That would be an utter disaster. If you think we had a collapse in bond markets under Liz Truss, it is nothing to what would happen under Polanski, who has said that he doesn’t think public debt matters very much because “it is money we owe to ourselves”.

That is nonsense: for one thing, around a third of UK public debt is owned by overseas investors. The Greens would drive Britain’s remaining entrepreneurs abroad and their policy to “abolish landlordism” would collapse the rental market, making it difficult for many of the party’s young voters to find a home. Energy prices would soar even higher than they already are.

Happily, I think the prospect of a Green government is still distant. Appealing to the Muslim vote in Gorton may have seemed a good wheeze, but it will count against the party in areas without substantial Muslim populations if it is perceived to be a single-issue Gaza protest group.

Less happily, I fear the result may well mean that we end up with a much more left-wing Labour Prime Minister in the short term. The lesson which many in the Labour party will take from this is that the government is floundering because it is not left-wing enough. The main threat, they will assert, comes not from Reform UK but from the Greens.

That makes it all the more likely that when Starmer goes – an event which has surely now been brought sharply forwards – it will be a Rayner or a Miliband who takes over, not a Streeting or a Mahmood. That itself will have dire consequences for the UK economy, and for fiscal stability. It is going to be a long few years before the next general election, due in 2029.