It’s a Wednesday night on Whitechapel Road in east London, and outside the London Muslim Centre they are queueing round the block. Hundreds, mostly under 30, have come to spend two hours listening to a few people talking about politics.  Related: Jeremy Corbyn 'would increase mandate if he faced leadership contest'  Inside a ground floor hall, there are already no empty seats. The twentysomething to my right stares intently at a news story on his phone about the junior doctors’ strike; in the row behind, they are excitedly debating the merits of Bernie Sanders. Eavesdropping on other conversations, I hear mentions of the Socialist Workers party, the refugee crisis, and a new and already famous – or, if you prefer, notorious – organisation called Momentum. “People in the Labour party see it as quite threatening,” someone says. That may well be true, but it is the energy and enthusiasm channelled by Momentum that lies behind tonight’s turnout.  To quote from its publicity material, Momentum is “the successor to the campaign to elect Jeremy Corbyn as leader of the Labour party”. It claims to have as many as 100,000 supporters around the UK, and to have spawned around 100 local groups, as well as playing a big part in other initiatives that aim to push well beyond traditional politics. Tonight is a good example: it’s the launch event of “People’s PPE” – started by Momentum activists in London who want to put on events with an academic tilt, and aimed at offering an alternative to the kind of politics supposedly enshrined in the Oxford University philosophy, politics and economics degree that has become a byword for the modern Westminster establishment.  The star turn is Guardian columnist and activist Owen Jones, who gives a speech, some of which he reads off his phone, about the Diggers and suffragettes; it’s delivered with his customary oomph. The aim is to explore some overlooked radical traditions in English politics, with two added twists: the discussion will be in a room next to a mosque; and the speakers also include Peter Oborne, the mischievous Tory columnist, who spends much of his allotted time praising Corbyn and Sanders for revealing “the bankruptcy of the old politics”.  As a radical event, it’s a bit of an anticlimax. Instead of the participative, break-into-small-groups format now common practice among the more imaginative branches of the political left, the proceedings follow a traditional model: the speakers talking for slightly longer than necessary, followed by questions and points from those brave enough to speak.  But you have to remember, it is not that long since it was commonly accepted that the young were no longer interested in politics, and of the Labour party was finished as any kind of popular movement. Since the 2015 election, 180,000 people have joined Labour and, whatever the perception of Momentum, the fact that 1,000 people will come out on a cold Wednesday night to listen to other people talking politics proves that something significant is afoot.  Among those I talk to is 25-year-old Jack Beezer, who works in financial software and has been to several recent Momentum events. He left Labour when he was 18, but rejoined before last year’s leadership election. “I was sick of them fighting over the centre ground rather than principle, and chasing the Conservatives to the right,” he says.  He voted for Corbyn. But does he think Labour can win the next election?  He paraphrases something he recently heard from Bernie Sanders. “There’s only so many times you can be told, ‘First put up with this, then things can change,’” he says. “Maybe by voting for what you believe in, you can actually get it.”  How close is Momentum to Corbyn, now he is leader? Speaking at the time of its launch last October, he said the organisation is a crucial part of how he and his supporters “need to unite and continue to build our movement to change our politics and win together in 2020”. John McDonnell, the shadow chancellor, believes it sits at the heart of how the new Labour might “transform our democracy and our way of doing politics”.  But others in the Labour party are a lot less convinced. They claim Momentum has a none-too-hidden agenda of wanting to get rid of non-Corbynite MPs, that its activists too often behave belligerently towards other party members, and that many seem to fixate on internal politics.  The recently sacked shadow cabinet minister Michael Dugher said in December that the aggression of Momentum members “is matched only by their stupidity”. Last month, east London MP, Stella Creasy, who was a target of leftwing anger last year over her Commons vote in favour of bomb attacks on Syria, said there was “emphasis by some in these groups on controlling the levers of power to select – or deselect – MPs and party officials” and concluded: “Groups like Momentum now appear to be draining the very energy from our political process they claimed to be promoting.”  If the rumours turn out to be true and Corbyn’s opponents try to topple him, Momentum will be at the heart of that drama  Momentum’s members reject all this. They say their Labour adversaries are as guilty of introspection and nastiness as anyone else, and claim everyone ought to respect the basic principles of loyalty and pipe down – even if Corbyn’s pre-leadership record as a serial rebel makes that a tricky sell.  In the midst of all this noise, it’s easy to forget that the politics of Momentum might be almost as complicated as the Labour party itself. While younger members talk about “narratives” and “engagement”, more battle-hardened elements focus on the party and its machinery. Only one thing seems clear: if current rumours turn out to be true and Corbyn’s Labour opponents try to topple him, Momentum will be at the heart of that drama.  Five hours before the People’s PPE meeting, I pitch up at a grim-looking office block next to Euston station, buzz the entry phone and go up a couple of flights of stairs into a warren of spartan rooms. This is Momentum’s HQ, provided by the transport and travel union TSSA, and staffed by four full-time staff and an array of volunteers.  My guide for the day is James Schneider, 28, an Oxford graduate and one of Momentum’s national organisers. His senior role has already made him a target for the rightwing press, plainly delighted by the fact that he went to Oxford University and Winchester school, and is therefore, as the Sun put it, “more Tatler Tory than socialist sympathiser”.  At the mention of this, Schneider shrugs. “If you’re on the left and you’re working class, you’re an envious class warrior. If you’re middle class, you’re a hopeless idealist who isn’t rooted in the practicalities of everyday life. You can’t win.”  At Oxford, he served as president of the Lib Dem society, which he puts down to the strange state of politics in the early noughties, and his youthful opposition to such parts of New Labour’s record as ID cards and the introduction of tuition fees – as well as the Iraq war. “I gradually read more, and moved farther to the left,” he says. At last year’s general election, he wanted Ed Miliband to win. “But I voted Green, as an anti-austerity gesture in a Labour seat.”  Schneider had spent the previous six years as a journalist; when Labour lost the election, he had just come back to the UK from Cameroon. He joined the party on 11 May, three days after Miliband resigned, had a conversation on Twitter with one of Corbyn’s backers, and found himself elevated to the core of the campaign. He was coordinating phone canvassing as a tsunami crashed through Labour politics, with new members signing up in droves – for full membership, or as “registered supporters”, who paid £3 to get a leadership vote.  Schneider went to his first party meeting in north London. “There were 18 people: six councillors, six friends and relatives, six new members. The councillors viewed it as an accountability exercise. ‘You’re interested in housing – OK, we’ll tell you what we’re doing about housing.’ And the new members were going, ‘No, no, you don’t get it. We want to do something about it.’”  This, he says, is the basic reason Momentum exists. “It’s trying to make the Labour party more participatory and democratic, and campaigning.”  But what of the current Labour atmosphere and all the internal bickering? “There was a revolt that took place in Labour, saying, ‘We want the party to be different.’ That’s going to be difficult. But I don’t think it means there’s some kind of civil war.”  What do people get wrong about Momentum?  “We’re not a party within a party. The idea that we’re all terrifying 1980s throwbacks, rulebook-thumping Trotskyite infiltrators – that’s just silly.”  But there are people from exactly that political background who are involved.  “True. But what’s going on is different. The world is profoundly different from how it was then.”  Schneider says Momentum breaks down into trade unionists, “Bennites and post-Bennites” (who share the background of Corbyn, McDonnell and a lot of Momentum’s older activists), and the younger members, who cut their teeth with the anti-tax avoidance activists UK Uncut or the Stop The War coalition. Thanks to them Momentum is “looser” than the Labour left of the past, he says: “It’s more movement, less party.” He pauses. “We think the party has not been sufficiently democratic or participatory, that it should be based on campaigns. It’s been too much of a vote-winning machine and not enough of a movement.”  This highlights another tension at the heart of Momentum’s politics. To create a movement is not the same thing as winning an election. I put this to Schneider’s fellow national organiser, Emma Rees, a 28-year-old from suburban Bristol who had just thrown in her job as a primary school teacher and decided to move to Barcelona when she volunteered for the Corbyn campaign and soon changed her plans.  The question I ask her is obvious enough: can Momentum appeal to people in Harlow, and Milton Keynes, and all the less-than-radical places Labour must win if it’s going to be in government?  “That’s the challenge,” she says. “But I think many people would be happier and have a better standard of living if we cooperated with each other more, and prioritised kindness, compassion and a sense of solidarity. Our society isn’t structured in that way, and we need to show people that we can do things in a better way.”  But can you successfully do that in five years?  “We’re not going to transform the entirety of society in that time. But I think we can start preparing the ground.”  My next stop is Ramsgate, on the Kent coast. On a chilly Wednesday lunchtime, 15 or so Momentum members are standing outside the jobcentre, protesting with local trade unionists against the stopping of local people’s benefits.  They have stickers announcing a just-launched Momentum campaign called “Poverty is a crime”, flasks of coffee and clipboards to take down the details of any potential recruits.  The Momentum group here came together in the wake of the general election, when Nigel Farage unsuccessfully stood for Thanet South, and a group, Thanet Stand Up To Ukip, made a brilliant nuisance of themselves. I met them then: a lot were over 50; many were part of that tribe who’d considered themselves thoroughly Labour, before the Blair and Brown years.  The organiser of the protest is 62-year-old Jackie Walker, who came to the UK from Jamaica and moved to nearby Broadstairs from London six years ago. An author, whose book Pilgrim State tells the story of her mother’s mental illness and her family’s grim treatment at the hands of social services, she has a long history as a political activist. We shelter from the cold in a cafe and she explains how she left Labour when Tony Blair moved to get ride of clause IV of the party’s constitution, which committed Labour to public ownership of industry. “I knew what that signified,” she says. “It was the end of the party as I would want it to be.”  But she rejoined in 2008, and went into overdrive when Corbyn stood for leadership. “I went anywhere, organised things, raised money and talked to people.” She is now vice-chair of Momentum’s national steering committee.  Why is there a need for Momentum? If so many Corbyn supporters have now joined Labour, why not just concentrate on the party itself?  “I’ve heard that,” she says. “I almost get bored with it. There are still a lot of people who don’t trust Labour, or don’t find party meetings friendly or accessible. Or they like what Jeremy Corbyn says, but are worried about what other Labour people are saying. So they’re biding their time. If I had my way, they’d all be members.”  What is the relationship with the local Labour party? “I think some people still find it difficult.”  Can she see why? “I can, but I think they’re wrong.”  Some Labour MPs seem furious, or scared – or possibly both.  “You know, that word ‘furious’: I wish they’d be furious about poverty. About the Conservatives. The membership has spoken, and they’re still going, ‘You know what, guys – you don’t really mean that. It’s because you don’t understand what’s going on. Really, you want to be on the right.’ Well, the membership have rejected the right in terms not just of the leadership, but of their policies. And that’s what they don’t quite get.”  If some of them were here, I suggest, they would probably say, look, we tried this. In 1983, we stood on a socialist manifesto, and look where it got us.  “I would say, I’m not interested in a party or a politics where what’s important is just winning,” she says. “And I don’t know that it’s about that for many people in Momentum. It’s about what we believe is right. And we believe that the politics of Jeremy Corbyn and John McDonnell are the right politics for this country.”  But if you don’t win elections, or make a serious attempt to, what’s the point?  “I don’t know why you’re saying that. Look at what’s happened to the right of the Labour party. Not even their own supporters want to vote for their policies. Why should anyone else vote for them?” Later, she adds: “The way you get people interested, and on fire, like we’ve seen with Jeremy, is to actually state your case. I am fed up of politics being a game. I want politics to be about ideology again.”  Watching a room full of people trade ideas about how to improve where they live is, in its own modest way, inspiring  Walker has pointed views about Labour MPs who are out of step with the views of their constituency activists. “If you have a real disparity, I think that’s a major problem. How is it all right to have a local MP who time and again goes against the wishes of their constituents? How is that democratic?”  This brings us to the controversial issue of deselection: activists moving against sitting Labour MPs and trying to replace them with more left-leaning politicians. Momentum’s official policy is to steer clear, but Walker is blunt: “I wouldn’t talk about deselection. I’d talk about selection. I think selection of MPs is a really crucial issue. And I think we should have the right to select our MPs. I don’t see why MPs have a job for life. Do you have a job for life?”  Six hours later, I take a seat at a Momentum meeting in Broadstairs, two miles up the coast. More than 40 people turn up. Once they’ve watched a 20-minute film picking through the region’s longstanding economic problems and the idea that Corbyn-style politics might offer some solutions, they talk. Watching a room full of people trade ideas about how to drastically improve where they live offers a spectacle that is not impossibilist or devoutly ideological, but detailed, practical and, in its own modest way, inspiring.  In the fourth row from the front, I grab a few minutes with Clare Oliver, a 44-year-old single mum who works as a cleaner. This seems to be her first ever political meeting; she says she only voted for the first time last year. “I live constantly on the poverty line,” she says. “I’m just looking for a way to make things better, really.”  What does she think of Corbyn? “I think he’s a breath of fresh air. Just that whole thing of breaking from how people think a politician should talk, and look. He seems a bit more real.”  Four days later, I am back at Momentum’s London HQ – or, rather, a Caffè Nero just across the road, where I spend an hour and a half talking to Jon Lansman. A 58-year-old Labour veteran who joined the party in 1974 and went on to work for that revered radical icon Tony Benn, Lansman spent last summer serving as director of operations for Corbyn’s leadership campaign. The fact that he is both Jewish and a lifelong activist on what used to be called the hard left puts him in an interesting place when it comes to suggestions of rising antisemitism in the reinvented Labour party: in a recent piece for the Jewish Chronicle, he warned against “allowing the trivialisation of antisemitism through its opportunistic misuse as a political football”.  Right from the start of Corbyn’s leadership campaign, he tells me, “I wanted to build a new left organisation.” If anyone has a claim to being Momentum’s founder, it is Lansman: he is now the organisation’s chair, a close confidant of Corbyn – and, as evidenced by his Twitter feed, one of the most energetic advocates of the reborn Labour left.  At the start of our conversation, he offers me a slightly wry assurance: “I’ve never been in any Trotskyist organisations, or far left groups. I’ve always been a Bennite.” Back in 1981, he was at the centre of the hugely divisive battle for the Labour deputy leadership between Benn and Denis Healey; seven years later, he organised Benn’s doomed challenge to the then leader Neil Kinnock. (“It wasn’t the left at its best,” he admits.)  Lansman is a hell of a talker, and we tumble through his views of Blair (“To all intents and purposes, a Tory… it was a very, very bleak period”), Brown (“A real Labour movement figure”) and Ed Miliband (“I was optimistic about Ed. He opened up debate”).  We then get to Corbyn, and the reasons he won. “He didn’t have any enemies,” Lansman says. “He didn’t appear to have any serious baggage.” There was also the fact that, as he sees it, the remaining disciples of New Labour had precious little real support. “The right have always claimed the silent majority as their base. But the Blairites never had anyone on the ground. That was always obvious to me.”  I rattle through what seem to be Momentum’s big aims: to bring people into the party, and provide Corbyn with a dependable base of support. He nods in agreement – then, unprompted, he mentions something else: “To some extent, I cannot escape presenting this as a contest between factions. Because there is Progress.” Lansman is referring to the Blairite organisation that, he says, was able to command only a tiny share of internal Labour support by 2015, as evidenced by Liz Kendall’s miserable 4.5% of first-preference votes in the leadership election. “Yet it still exercised massive influence” – training candidates to ensure they won nominations for safe seats, for example, and, as the Labour left sees it, using networks of influence to secure important positions in the party. Part of Momentum’s job, he says, is to redress the balance.  But what if faction-fighting consumes the party to the extent that the battle with the Tories recedes into the distance? “I don’t want the Labour party to become a faction fight,” Lansman insists. “What I want is a level playing field. I want the Labour party to be able to have a democratic debate.”  What does he make of all that talk about MPs – Blairites, perhaps – toppling Corbyn, maybe after the EU referendum? “I think it’s possible that people might move on Jeremy,” he says. “And we have to be prepared for that. I think it will be unsuccessful, because I’m absolutely confident that Jeremy has the support of the membership, and that we can beat off any challenge.”  We do have to restrain people. That’s why we’ve got a very clear code of conduct, about what is and isn’t acceptable  So is Momentum quietly preparing for some kind of attempted coup?  “Erm… we’re not making preparations. But we now have local groups all over the country which we did not have in June last year. We have a database of supporters all over the country who we are communicating with. We are therefore in a very much stronger position than we were. We’re working on recruiting a lot of those people who paid £3 to be registered supporters as full members of the party. And a lot of them have joined.”  In what he says next, there is just the faintest glint of menace. If there is an attempted coup against Corbyn, “we will not just recruit everyone who voted for him as a registered supporter last time. We’ll recruit more. A lot more.”  We talk a lot about Momentum’s youthful energy, and events such as the People’s PPE meeting, but I also bring up some more difficult topics. It’s a sign of how fevered the Labour party feels at the moment that few MPs will talk on the record about divisions in their constituencies; off the record, one MP will tell me about “Momentum flashmobs” suddenly turning up at meetings and spreading disquiet. Another told me about a group of Momentum activists in his local party who habitually “wind people up so much that they just leave the room – heckling, proposing resolution after resolution, and not allowing any kind of debate to unfold”. Their basic aim, as far as he can tell, is to make life for the other people at Labour meetings as unpleasant as possible. What does Lansman make of that?  “Well, I’m not in favour of unpleasantness.”  That’s nice, I say. But are he and the people at Momentum keeping an eye out for that kind of behaviour?  “We do have to do that. We do have to restrain people. That’s why in Momentum, we’ve got a very clear code of conduct, about what is and isn’t acceptable.”  This reminds me of something Schneider told me, about a “code of ethics” that people in Momentum sign up to. “In lots of meetings I’ve been to, people have said, ‘Think twice before you put anything on Twitter’ and all the rest of it,” he said. “Because we are being trolled, by a small but vocal and well-amplified group of MPs, who are using smear attacks in the rightwing press.”  As if to illustrate his point, not long after we speak, the MP and former chair of Progress, John Woodcock, pronounces a Corbyn performance at PMQs to be a “fucking disaster”, and a tweet apparently posted by a Momentum activist in Manchester responds referring to Woodcock’s “mental health”; a remark that is subsequently branded “disgraceful” by Labour backbencher Angela Smith, whereupon it all goes off again. In a sign of how surreal all this has become, senior members of Momentum are adamant that in several instances, fake Twitter accounts have been set up and used to sully their name.  “You know,” Lansman says now, after a pause, “Jeremy has amazing self-control. I don’t have the same levels of self-control as Jeremy. I do sometimes get angry and lose my rag. But I’m only human. I don’t think it’s the right thing to do. We should be polite and agreeable and comradely with everybody.” Not for the first time, he flips the suggestion of nastiness around, and focuses it on those in Westminster who still cannot abide Corbyn’s leadership. “The venom is pretty horrible. There really is deep malice inside some of the people who routinely attack him.”  A man dressed in cycling gear passes our table and butts in. What he says might just as well apply to the anti-Corbyn elements in Labour as to Lansman and his Momentum comrades, but he says it with real urgency and anger: “Can we stop having arguments amongst ourselves and start having arguments with the Tories? It’s just destroying the party.”  That’s you told, I say to Lansman. And me, possibly. Either way, he’s obviously worried.  “I understand that,” he says and, just for a moment, he seems lost for words.
It is a breakaway group intent on dragging Labour left and getting Jeremy Corbyn elected. But who are Momentum’s members, and will they achieve their aims – or tear the party apart?