I'M not sure how the sight of Peter Mandelson, smoothing his way around the Labour Conference this week, like the cat who got the cream, will go down with the voters. He wasn't called the “Prince of Darkness” for nothing. But his smiling face certainly put the wind up Labour activists. His suggestion that New Labour is back infuriated those party members, around half according to YouGov, who still support Jeremy Corbyn.

Factionalism is the original sin of politics, and no one does it better than Labour. It has been indulging in internal culture wars almost since it was created. The division between the socialist left and social democratic centrists, which first broke the party apart in 1931 over Ramsay MacDonald's spending cuts, has never gone away.

It is more than an indulgence; it is now an addiction. There is nothing more intoxicating than accusing your own leader, as Mr Corbyn did this week, of “propping up the rich and powerful”. The resignation of the last Corbyn ally in the shadow cabinet, Andy McDonald, over the leadership's opposition to a £15 minimum wage, was received with rapture by the left. Yet its impact was to divert attention from the the most important speech of the week, by the shadow chancellor, Rachel Reeves, promising a quarter of a trillion in green investment over the next decade. But it played well on Twitter.

Whatever the merits of a £15 minimum wage (currently £8.91) there was never any prospect of Sir Keir Starmer offering an uncosted pledge at this conference, which is all about reassuring voters of Labour's fiscal rectitude. Even Labour stewards at Brighton were offered less than £10 an hour. Sir Starmer hasn't even agreed to restore the £20 cut in Universal Credit. His speech today will be all about what he isn't doing.

Read more: The message is clear: Starmer isn't working

Nor did the Deputy Leader of the Labour Party, Angela Rayner, help matters by attacking Tory “scum”. She claimed this is how people speak in “northern working class towns” which is patronising and wrong. A YouGov poll showed that 71 per cent of working class voters in the north, and elsewhere, think it is unacceptable to call political opponents scum. You'd never hear Nicola Sturgeon call anyone that (even Alex Salmond). She is still in touch with her working class family and community and knows how badly such language goes down.

But again, it played well on Twitter – unlike Sir Keir's attempt to bounce the party into restoring the electoral college for electing the party leader. Under his scheme, Labour MPs and the unions would have vastly outvoted the party membership, which currently elects the leader under one member one vote. The move was presumably intended as a show of strength, but it only confirmed his relative weakness. In the end, Sir Keir got a modification of the rules meaning future leadership candidates would require the signatures of 20% of Labour MPs instead of 10%. It will also be harder to deselect MPs. But a historic turning point it was not.

What Sir Keir is trying to do is become a British Olaf Sholz, the leader of the centre-left German Social Democratic Party, who has just won the German general election, reversing years of decline for his party. The SPD's mix of fiscal prudence and green rhetoric is exactly what Ms Reeves was offering to the voters on Monday, before she was blown away by rows over bad language and whether only women had cervixes, another issue that dominates social media and is incomprehensible to voters. For the record, Sir Keir thinks men can have cervixes too, or at any rate “it shouldn't be said” that women have a monopoly on female reproductive anatomy.

Read more: So, First Minister, do you think a woman is an adult human female?

Herr Sholz does not lead a party divided in the way Labour is. The explicitly socialist left in Germany is hived off to Die Linke, “The Left”, which has a very similar agenda to the Corbynites: nationalisation, high tax, nuclear disarmament. This is unlikely to happen in Britain because of our First Past the Post voting system. Die Linke can expect to gain seats in parliament; Momentum, if it were to become a party rather than a faction of Labour, would probably gain none.

So when he speaks today, Sir Keir knows he has a fight on his hands. He has an internal opposition which may no longer be called the Militant Tendency, but is just as militant as the old Trotskyite entryists were in the 1980s. Indeed, they may be harder to oppose because they seem to be more interested in identity politics and gender than Marxism. Sir Keir is a middle-aged white man, and therefore racially suspect in the eyes of those who believe in the doctrines of white privilege and patriarchy. This is a conference where a platform chair said there were “too many white men putting their hands up” to speak.

 

Shadow chancellor Rachel Reeves with Sir Keir Starmer yesterday

Shadow chancellor Rachel Reeves with Sir Keir Starmer yesterday

 

Militant only had the power of print, the newspaper of the same name, that was distributed by slogan-chanting activists. The Labour left today have a new and potent mouthpiece in social media, especially Twitter, whose centre of gravity is far to the left of both Sir Keir and most UK voters. Social media is a closed system, an algorithmic echo chamber, in which populist politicians, like Angela Rayner, hear their words reflected back bathed in approbation. It's pretty much all they hear now.

Blairite is a dirty word on Twitter, many of whose denizens regard the former Labour leader as a war criminal. Indeed, the left seems more hostile towards Mr Blair right now than Boris Johnson, whom they just regard as a clown. Sir Keir's speech today will be dissected, derided and then dismissed by Labour's many Corbynites who see him as Blair redux. They'll say, with some justification, that he is talking like a Tory by ruling out common ownership, not reversing benefit cuts, not committing to increased taxes.

Some on the left believe Sir Keir is weakened by this week's divisions and can be forced to resign. Labour often accuse Tories of fomenting a culture war, but the most vicious culture war is in the Labour Party, and it is only just getting started.

Our columns are a platform for writers to express their opinions. They do not necessarily represent the views of The Herald