A watershed has been crossed. The two-party system is lifeless and the place this all finally ends up nobody is aware of: ANDREW NEIL

British by-elections have long been a political ­spectator sport. A boisterous ritual to give the ruling powers-that-be a bloody nose – but the result soon ­forgotten and rarely of much long‑term significance.

Not Gorton and Denton: ­Thursday’s vote in that south ­Manchester constituency is one for the history books. A watershed has been crossed, a new era in British politics has begun.

It’s not just that the radical Left Greens won their first ever by-election by an impressive majority, though that is historic in its own right. Or that Labour came a poor third in one of its hitherto most secure seats, though that is remarkable, too. Or that Keir Starmer’s job security is once again on the line, though it certainly is.

The real significance – the political game-changer – is that it marks the demise of the Labour-Conservative two-party system that has dominated English politics for more than a century.

In the 2024 General Election the combined Labour-Conservative vote share in Gorton and Denton (which Labour won comfortably) was almost 60 per cent. On Thursday it was just over 27 per cent – barely a quarter of the ­voting public.

In stark contrast, the combined vote of the two insurgent parties – Reform and the Greens – was just shy of 70 per cent.

If that’s not a sea-change in ­British politics then I don’t know what is.

The country has seriously fallen out of love with Labour and the Tories, the core vote of both now a fraction of their former formidable numbers. Parties of the Populist Left and Right are calling the shots.

Hannah Spencer celebrates with Green Party leader Zack Polanski. Her victory is an indicator that the populist Left and Right are calling the shots now, writes Andrew Neil

Our politics is heading in a French direction where the Left-wing La France Insoumise (France Unbowed) and the radical Right National Rally have already replaced the traditional parties of the ­centre-Left and centre-Right.

Where this ends up nobody knows. Perhaps we should now pay as much attention to French politics as we do to America’s.

For the Tories it was their worst by-election performance ever. But they were never in contention, so their vote was squeezed to a minuscule 2 per cent (not even big enough to qualify as a hard core).

Labour in general and Starmer in particular were the big losers on the night. In reality, it was above all a ­personal defeat for the Prime Minister.

He had barred the one candidate who might have won it for Labour – ­Manchester Mayor Andy Burnham – for the entirely self-serving reason that he feared a leadership challenge should ­Burnham return to the House of Commons.

He poured campaign resources into the seat, even encouraging the idea Labour was winning by going to the constituency himself (something ­sitting PMs rarely do unless they’re sure victory is in the bag).

It was Starmer who personally signed off on an election strategy based on a lie – that only Labour could beat Reform – and which, incredibly, involved ignoring the Greens entirely, even after it was clear they were a force to be reckoned with.

To such an extent that the Greens were erased from Labour polling charts even when they were neck-and-neck with Labour, in the way members of the ­Stalin-era politburo in Soviet Russia would be removed from official photos after being executed or exiled to the gulag.

So Starmer owns this defeat, even if Lucy Powell, his Labour Party deputy, a senior Manchester MP and not always his biggest admirer, was complicit in spearheading the campaign, regularly feeding us nonsense about how warm the reception was for Labour campaigners on the doorstep and turning ‘only Labour can beat Reform’ into a mantra (devoid of ­substance, as it turned out).

Above all Labour’s humiliating defeat is proof positive, for those still in any doubt, of Starmer’s monumental, deeply engrained unpopularity among voters. Which is why ­speculation is swirling once more around his leadership.

His party knows he’s a dead man walking, haemorrhaging votes to Reform on the Right and now, more seriously, to the Greens on the Left. It just can’t muster the gumption to get rid of him, partly because (unlike the Tories) regicide is not in Labour’s DNA and, more significantly, none of the likely pretenders to the throne has yet managed to get their ducks in a row.

Keir Starmer is a dead man walking, says our columnist. And after the humiliation of Peter Mandelson came to be seen as the symbolic final demise of New Labour, Gorton and Denton has now buried it.

One of them, Angela Rayner, who had to resign from the Government over unpaid property taxes, was quick out of the blocks yesterday tweeting on X that ‘voters want the change that we promised… we have to be braver.’ She added that it was ‘time to really listen.’

I was about to contribute (helpfully, of course) my tuppence worth when I noticed the ability to ­comment had been turned off. So much for listening.

In fact, what she says makes no sense – Labour’s 2024 manifesto was specifically drafted to avoid any radical change. Unless you see her words as code for moving Left, which they are, much further Left than the manifesto ever indicated.

This process is already under way: Starmer has leaned Left to save his skin during previous leadership crises. Now its left flank has been breached by the Greens, Labour will be dragged even more to the Left; dragged ­willingly because further Left is where Labour’s heart lies.

The humiliation of Peter Mandelson has been depicted as the symbolic final demise of New Labour. But ­Gorton and Denton buried it.

Starmer was already under internal party ­criticism for trying to out‑Reform Reform. That gambit crashed and burned in the by-election. The lure of the Left will now prove irresistible.

Labour MPs and activists are already speaking approvingly in private of various Green policy positions, such as they are. So if the Green Party is now effectively going to be calling some of the governing party’s shots it’s high time its policies were subject to rather more rigorous public scrutiny.

The Greens have got away with spewing out bilge, largely unchallenged, on everything from drugs to defence on social media (where some of the young lap it up).

Their gobby new leader, Zack ­Polanski, has been generally treated with kid gloves by broadcasters. ­Contempt bordering on derision is their default position when dealing with Nigel Farage and other Reform politicians. Benign scepticism is the worst they can muster against Polanski, which has enhanced his undeserved ­reputation for being a breath of fresh air in our politics. In fact, he’s a blast from the past.

Much of what he stands for is a throwback to the pseudo-Marxist dreams of late Sixties student ­revolutionaries (when I was at university and saw it all first hand). Unilateral nuclear disarmament and destruction of our Trident missiles. The removal of any American nuclear weapons on British soil. Withdrawal from Nato, leading to its demise. These were the policies of the Marxist Left 60 years ago, as they are Green policies today.

Zack Polanski is proposing that we rejoin the EU, legalise prostitution and encourage the madness of open borders

Also a ‘non-offensive defence strategy’ (whatever that means) and shifting money from defence to ‘peace promotion’ (no idea what that means either). Any attack on Britain would be met by a ‘legal response’. So even as the enemy missiles rained down on us the lawyers would still be making money. It is, in effect, a pacifists’ charter.

Yet Polanski also proposes that we rejoin the European Union.

The idea the EU would want anything to do with a country hellbent on the destruction of the ability of western democracies to defend themselves – at a time of autocratic threats, especially from Russia, as grave as anything we experienced during the Cold War – is for the birds. It’s as if the ­invasion of Ukraine never ­happened. It illustrates a mixture of Green naivety and stupidity which needs to be exposed.

The madness doesn’t stop there. Polanski proposes open borders, so that anyone and everyone from around the world would be ­entitled to come to live here ­(suggested slogan: ‘Vote Green, let ’em all in’).

More than that, even illegal immigrants (if such a concept exists in Polanski World) would not only be given amnesty but be entitled to a ‘free’ home and NHS care from day one. Well, why not?

Deportations would be banned. Immigrants would be entitled to work if they wanted. If not, no problem – they’d qualify for a ­‘universal basic income’ of £89 a week (plus benefits).

Detailing all this gives me some sympathy for the broadcasters – just where do you start unpicking such a fantasy agenda?

Then there’s the Green plan to legalise all drugs, including heroin and date-rape drugs. But no need to worry: Children will be taught in primary school how to take drugs ‘safely’.

Prostitution would also be ­legalised and hardcore porn made more accessible, which will have its appeal for some.

Polanski is also a radical when it comes to trans rights, insisting a woman can have a penis. What a wonderful Green world to look forward to!

If you can afford it. The Greens also talk of an extra £50billion in taxes (on a country already with the highest burden in 70 years), of which ‘only’ 10 per cent would come from a new wealth tax.

Curiously, newly elected Green MP Hannah Spencer barely mentioned the environment in her victory speech. It seems the Greens don’t dwell much on green issues these days…

Of course, no wealth tax anywhere in the world has come close to raising £50billion a year. But, hey ho, who’s counting? And by the time Polanski ever came to power, the people liable to pay it would be long gone anyway.

Curiously the Green Party doesn’t dwell much on green issues these days. It’s all for the dash to Net Zero, of course, but it’s more enthusiastic about nationalising water, energy and transport. In her overlong and ­solipsistic ­victory speech in the early hours of Friday morning the Green’s newest MP, Hannah Spencer, barely mentioned the environment.

Communism, class warfare, cocaine and ketamine seem a more potent Green electoral brew to appeal to young metropolitans these days than hugging trees or saving polar bears. So instead of global warming there was much old-fashioned Marxist class rhetoric bashing the billionaires and bigging up the workers.

Plus, of course, unreserved support for the Palestinian cause (which often borders on sympathy for Hamas) with Israelis dismissed as the irredeemably bad guys, a crucial pitch in the Green wooing of the large Muslim population in the Gorton and Denton constituency. In Green propaganda designed to hook the Muslim vote (some of it in Urdu), radical trans rights, drugs and porn were curiously underplayed.

Labour will clearly not follow the Greens down all these roads. Some of its policies are too ludicrous even for the Corbynistas. But it does indicate Labour’s direction of travel: More tax, more spend, more welfare, more state control, ever closer ties with the EU, more support for the Palestinian cause, no chance of a real boost to defence spending.

In a sense, it doesn’t really ­matter if Starmer stays or goes. The die is cast: This is the Leftward direction Labour is taking regardless of who is the leader.

Under Rayner or Ed Miliband (perish both thoughts) it might go even faster – at least until the bond markets, where governments go to borrow, bring it to a crashing halt.

One final fundamental lesson from the by-election: There is no way Labour will be able to form another government on its own, whenever the next election is held.

Farage always thought Gorton a long shot, but 29 per cent of the vote in an unfriendly seat means he’s more confident than ever Reform will come first in the ­English local elections (even picking up some outer London boroughs), second in elections to the ­Scottish Parliament and first or second in Wales.

So Reform remains on track, for now, to be the largest party in the next Westminster parliament.

If the Left wants to stay in power it would probably require a Labour-LibDem-Green coalition to secure an overall majority. Naturally, such a prospect is enough to cause palpitations in the hearts of all right-minded folks (not to say a rush to the door).

In reality, it would be a shambles, and collapse in chaos and recriminations within months, if not weeks, amid economic and political crises. Fresh elections would likely produce a massive centre-Right majority in reaction.

Of course, a lot of damage would be done getting from here to there. But nobody said this new age of British politics was going to be plain sailing.