Let me introduce you to Bob Blackman, Tory MP for Harrow East since 2010. Blackman is quite the charmer. He doesn’t just oppose equal marriage: he has called for the reintroduction of Section 28, the anti-gay law that banned the so-called promotion of homosexuality by local authorities or schools. He has retweeted propaganda shared by far-right thug Tommy Robinson, and hosted an anti-Muslim extremist who justified the genocide of Burma’s Rohingya Muslims in parliament. Here is an MP who will help the hard right take over the Conservative party and, with it, the country. And if there is one thing that may help Blackman, whose parliamentary majority shrank at the last election, and the Mogg-Johnson ascendancy, it is a coming Labour split.

There are said to be at least two centrist plots. The first is orchestrated by Simon Franks, a delusional multimillionaire almost no one has heard of, who believes he can use his wealth to become Britain’s Emmanuel Macron. It seems a centrist party is this season’s must-have accessory for the discerning businessman. Then there is a small faction of Labour MPs, led by Chuka Umunna – who a year ago declared “Unity is the watchword, government is the aim!”– and Chris Leslie, who are reportedly privately discussing when to leave. Relations between the two factions are acrimonious. In the mix are the ghosts of Blairite past, like former Blair speechwriter Philip Collins – who is open that he sees stopping a Corbyn government as a mark of success of any new centrist party – and former Blair chief of staff Jonathan Powell.

It seems a centrist party is this season’s must-have accessory for the discerning businessman

The political shape of a new party is clear: the likes of Chris Leslie have been remarkably candid about what they believe in. After Labour’s 2015 defeat, Leslie blamed Ed Miliband for being too leftwing and anti-business, and for demonising private landlords, and he castigated Corbyn’s anti-austerity politics. A new party will be a pro-cuts, pro-privatisation stitch-up, bankrolled by wealthy business interests. It will be a scam: a return to the very politics which bred popular disillusionment and plunged the country into crisis in the first place.

But in a sense, that is hardly the point, because such a party will never assume power. The SDP was led by political giants known to millions of Britons, and yet it won a paltry 23 seats in 1983, merely helping to gift Thatcher a landslide. According to sources, Umunna believes the surge in his majority last year was down to his anti-Brexit stance; yet that hardly explains how uber-Brexiteer Kate Hoey’s majority dramatically increased in the neighbouring remain citadel of Vauxhall.

Claiming the public craves a new centrist party is a bold position to take a year after an election in which the combined share of the two main parties leaped to the highest level since 1970, and in which the Lib Dems were humiliated. The centrist fixation with Macron as an example to follow is instructive. The French president won less than a quarter of the vote in the first round, little more than three other candidates ranging from the radical left to the far right. Polling showed that any candidate would beat fascism, as Macron went on to do, and that a large majority voted for him primarily to stop a far-right Le Pen triumph. And the driving forces behind a new party have one striking feature in common: they have spent the last three years demonstrating that their sense of entitlement is only matched by their complete lack of understanding of why millions of citizens are so desperate for radical change. “Remember these people have called every judgment wrong since 2015,” one non-Corbynite shadow minister tells me, “so going and creating some new party wouldn’t now surprise me.”

To understand the real threat posed by a split, look to Battersea. Here the Tories triumphed with a near 8,000 majority in 2015; two years later, Labour won a majority of 2,416. A party of snake-oil salesmen will crash and burn here, but even if it attracted a meagre share of Labour voters furious over Brexit, that could be enough to shuffle the constituency into the Tory column. Taking just a couple of percentage points from Labour’s national tally could gift the Tories a majority. If I was a strategist for the Tory hard right, desperate to reshape the country in the image of Jacob Rees-Mogg, would I desire anything more?

Most Labour MPs are implacably opposed to a split, including many on the right, such as Wes Streeting. MPs like Caroline Flint and Gloria de Piero may hail from the party’s Blairite wing, but they represent solidly leave seats and would never countenance joining an anti-Brexit party. But those few plotting to leave will orchestrate a scorched-earth campaign until they finally make the leap.

The response of some on the left may be “good riddance”. Some in Labour’s leadership worry that if the party wins a narrow majority, a faction of 15 fervently anti-Corbyn MPs will make governing impossible. But a centrist party will enjoy feverish support from the media, including a centrist commentariat desperate to regain political relevance. After an initial confected honeymoon, it will undoubtedly prove a humiliating failure, but it need inflict little damage on Labour in order to leave Boris Johnson and Jacob Rees-Mogg as Britain’s political masters. An unspeakable tragedy, and all for the sake of an entitled few.

• Owen Jones is a Guardian columnist