Shortly after Jeremy Corbyn swept away his rivals in the leadership election two years ago, one Labour left MP sidled over to me in Brighton, and chuckled: “We are the masters now!”

That same year, I witnessed the spectacle of Labour First, the old fashioned, non-Blairite, right-wing faction, holding its first conference rally outside a Brighton pub. It was packed with angry speeches attacking the new leadership.

Neither side of Labour was at all used to its new position. The left’s lot at the time was very much, as Tony Benn called one volume of his memoirs, office without power. Corbyn had won the leadership, but his shadow cabinet was stuffed with leakers and lurkers, and he had few supporters within Labour’s influential HQ.

The leader’s own office, for its part, got off to a bad start. According to some close to the action, key individuals in Corbyn’s first leadership campaign had sought to exclude others in order to consolidate their own positions in the new regime.

Meanwhile, it was arguably the first time ever that Labour's right wing had been the outsiders. Standing outside that pub, it was plain they had forgotten how to do it. The speeches from the likes of Progress director Richard Angell, Labour First chief Luke Akehurst and Rachel Reeves didn’t sound insurgent, but shouty and defensive. “I think this is quite good for us,” one leftwinger said to me afterwards. “It makes them seem a bit nuts.”

That was, however, all two years ago. This week, Labour First and Progress are not only each holding their own rally, but they have also jointly produced their own guide to conference. On its first page, it admits it is “belatedly mirroring” the guide produced for years by veteran NEC member and Campaign for Labour Party Democracy (CLPD) secretary Pete Willsman. Pleasingly, it looks every bit as anachronistic as Willsman’s guide.

Though the Labour left has grown more used to being in control, the recent election result has once again given it much to catch up on. When the vote was called, many thought Corbyn could either be immediately butchered in a post-election coup, or face an orchestrated challenge at conference.

Now he is unimpeachable. But as well as boosting morale, this provides a challenge for the left. The two leadership elections, after all, provided not just a strong purpose, but an immediate, practical task to complete, and common ground for a fractious coalition.

Let’s not forget the struggles within the left that emerged when there was no compelling cause to put them aside for. Momentum, the organisation set up out of Corbyn’s first campaign, is a case in point. Earlier this year it was the site of an epic showdown.

Jon Lansman, the veteran of Tony Benn’s 1981 deputy leadership campaign, had been working behind the scenes to set up a new left organisation long before anyone dreamed of electing a left leader so soon. When Momentum was founded he was elected its chair.

But he soon found his position challenged by activists who wanted Momentum to take its own policy positions — decided by delegate conferences. Many of these activists were close to the Alliance for Workers Liberty (AWL), a Trotskyite organisation with an entryist strategy. Lansman’s supporters, for their part, said Momentum should prioritise organising within Labour rather than creating parallel structures. They favoured an one-member, one vote approach to decision making.

When Momentum froze out its ultra-left with a shake-up to its governance, a number of activists split off to form “Grassroots Momentum.” As well as the AWL, its supporters included Labour Representation Committee activist Jackie Walker and Fire Brigades Union leader Matt Wrack. This organisation now appears to be moribund, but many of the same activists have put their energies into a magazine called The Clarion.

Now the Labour left is facing the potential of a more significant split — over Brexit. Several groups on the far-left, including the AWL and Socialist Action, have taken an aggressively pro-EU stance following the referendum. This is anchored in a belief in retaining free movement, but it occasionally sways towards remaining in the single market and holding a second referendum on EU membership.

Oddly, such groups now find themselves allied not just with soft-left Europhiles but with Labour’s right wing. Progress chair Alison McGovern, after all, is behind the new Labour for the Single Market campaign.

Many others on the left are resistant to this approach — either out of a desire for Labour to keep its options open, or out of a belief that free movement and the single market are the bedrock of EU neoliberalism and undermine wages. The GMB union has recently adopted a stance critical of free movement.

Marcus Barnett, an elected RMT representative and member of the London Young Labour executive, says the party must work hard to maintain the “very, very fraught coalition” of voters it has always represented.

“It's more of a case of rebuilding the whole fraught coalition now, rather than actively negating one side of it and allowing them to pursue other electoral routes, such as Ukip, or even in some places the Tories these days,” he says. “It's whether the Labour left itself can navigate that coalition as well, that's a question for ourselves.”

Brexit, Barnett says, is “clearly causing issues” for the left. “I think the right of the party, the real right of the party, can appreciate the difficulty on the ground, much better than the soft left can, which is why they've been good allies so to speak, to Corbyn in this situation.”

He draws a distinction between Progress and Labour First, saying that the latter, for all its factional manoeuvrings, has taken a more constructive approach since the election. “Some of the people you associate with Labour First, such as John Spellar and John Mann, published fairly comradely articles discussing the future of the Labour Party and the heartlands. I don't particularly agree with the criticisms but they're fraternal disagreements now.

“I'd be happy to have discussions with these people, rather than the bile you get from the dishonest sycophants [of Progress]. I really don't mind having these people around, they're people who can accept, in a broad way, the manifesto.”

Barnett is not the only one to believe that Labour First is now the more significant force on the right. Even ahead of the election, a key left operator who I spoke to said that Progress was becoming increasingly irrelevant.

And one MP on the old right says he can see the split clearly emerging. There are figures on the Progress wing, he tells me on the condition of anonymity, who are serious about the prospects of establishing a new centre party. His wing, on the other hand, is “used to doing deals with the likes of the old Communist Party.” He still can’t stomach a certain section of Labour’s new left-wing members, which he sees as having no understanding of the party’s history, processes and structures.

So it’s not just on one side that there’s appetite for accommodation, or resistance to it. But there is a major stumbling block. That’s the fact that so many MPs don’t hail from the traditional union right, but the trajectory that saw so many go from Labour students to ministers’ special advisers to safe seats.

The more sensible members of this clan are re-evaluating. Just look at Chuka Umunna’s recent outspokenness over blacklisting. But those who cannot find a cause more worthy than staying in the single market are more likely to find themselves on a collision course with their constituents in the coming few years.

At the centre of one of the most bitter factional rows of recent years was Rhea Wolfson, now a member of Labour’s ruling NEC. When she first put herself forward as a candidate, the former Scottish Labour leader Jim Murphy, a member of her constituency party, urged fellow members to block her. She was subsequently accused by leading Progress figures of believing that Labour should not aim to win elections.

Now, however, she is optimistic about the future. “When the party was at its most divided, I think there was a genuine distrust of the intentions of the people on the other political side of the party,” she says.

“That’s very difficult to build any kind of genuine, coherent, allied party under that. I believe there were people on the right of the party who genuinely thought that those on the left, those who supported Corbyn, wanted to see the party burn for ideological purity.

“I hope that now we have done so well, we have shown that we’re an effective party of the left, that want to be in government.”

Wolfson, who stood in the Scottish constituency of Livingston in June, knows it will not be easy to make the final leap — especially north of the border. But she says that in spite of Labour still struggling to attract support among certain demographics, there is no need to cede ground to the right.

“What I personally want to see is an industrial promise to every abandoned community across this country," she says. “It’s industry, not immigration — that's the question we fundamentally need to answer. That is the winning solution.”