My online registration had been accepted, as had the £5 fee for my ticket. And yet I confess to feeling a little apprehensive as I arrived at the Lambeth Academy for the launch event of the local branch of Momentum, the Corbynites’ grassroots campaigning operation.

After all, the Labour leader’s followers aren’t famously keen on journalists – nor are they that fond of Tories. The memory of yelling, spitting crowds outside the Conservative Party Conference is still sufficiently fresh that I don’t feel the need for a re-run.

As it turned out, I needn’t have worried. Having merrily accepted a hard left leaflet from a man outside the event as a convincing prop, I dodged a clutch of people wielding petitions and gave my name at the desk. Ticked off on the registration list, I was issued with a blue ticket torn from a raffle book, and I was in: my evening with Momentum had begun.

A crowd of around 150 people occupied the school hall, beneath motivational transfers on the walls declaring “Unity” and “Ambitious”. They were a mixed group – in age, in race, and in their reasons for being there. A disgruntled ex-Labour councillor, trade union officials and established local single-issue campaigners mingled with genuinely enthused new recruits to Corbynism and grizzled old veterans of every faction fight of the last three decades.

Accepting the leaflet outside had been unnecessary – copies were placed on every seat in the hall. It made troubling reading for anyone concerned that Momentum is a vehicle for far left entryism into the Labour Party. At the top, its authors declared their credentials: “Socialist Party – formerly Militant”. It seems the “new politics” may in fact be an expression of something as old as the hills.

The content was no less stark or blunt than the branding:

“KICK OUT ALL THE WARMONGERS…it was a serious mistake to grant a free vote to the Parliamentary Labour Party…Previously, regarding war on Iraq or Assad in Syria, anti-war politicians could cite the need for UN backing in the knowledge that it would be vetoed by Russia and China…” “TWO LABOUR PARTIES IN ONE…there are two Labour Parties – those who support Jeremy Corbyn and those who seek to use any opportunity to remove him…Unfortunately, Corbyn and McDonnell have been placing ‘party unity’ – ie the right-wing calling the shots – above boldly taking steps to transform the party in a leftward direction…One vital demand to help transform the Labour Party in that direction should be for all political forces that have been fighting austerity to be welcomed into Labour. This means removing all bans and proscriptions against socialists…This should include the right of members to make elected representatives accountable. Mandatory reselection is only a challenge to those who refuse to carry out the wishes of the people…” “WE CALL FOR A vote of no confidence in Chuka Umunna…”

In short, it was a dual demand for entryism and for purges – and at minimum the organisers of this meeting had no problem with Militant distributing inside the venue. As if on cue, a man in a pink t-shirt sat down next to the couple behind me, introduced himself as being from the Socialist Party and began to present “talking points” for them to use should they be called to ask a question. There were now “two Labour Parties in one”, he explained, and “the people” ought to be in control. His final point was that Chuka Umunna must be deselected.

To their credit, the couple on the receiving end of his briefing balked at this last argument. “I don’t agree…that isn’t what Momentum’s meant to be about,” one objected. “You don’t have to say it if you don’t agree. I mean, you wouldn’t make a good case if you didn’t believe it. It’s up to you,” came the reply, and off he went to speak to other audience members.

Belatedly, the meeting began. After a short preamble about the long struggle for the left to be heard in the Labour Party, the first two speakers addressed stock local issues: Ruth Cashman of UNISON discussed Lambeth Council’s plan for library closures, and Khi Rafe of Unite discussed the impact of spending cuts on the council’s mostly black and ethnic minority workforce. Neither speech was particularly new, but the presence of both was a clear message: Momentum enjoys support from the union establishment.

The third panel speaker proved more interesting. Marlene Ellis, a Labour Party member and Momentum activist, was on the platform as the formal representative of the Lambeth Momentum branch. This was the introduction to the organisation, and the first official insight into their intentions. As she stood to speak, a man in the audience yelled “What are you going to do about Umunna?” With a smile, Ellis simply replied, “That’s a very good question…”

Anyone expecting a speech railing against the Conservatives was in for a surprise: her main target was Blairites and other untouchables within the Labour Party, and specifically within Lambeth:

“Momentum supports the Labour Party and its councillors, but only on the proviso that they work within the spirit of our new Labour politics.”

As ever, the proviso is crucial. Members of Progress, the Blairite pressure group, evidently don’t make Momentum’s grade:

“I want to talk about the company called Progress…There are a number of our councillors who are members of Progress, and I want to suggest to you that there is a conflict of interest between serving Progress and serving our communities in Lambeth as a councillor…[applause] “ “From a Labour and Lambeth perspective, Progress wants to dominate the Labour Party at the centre and it clearly has huge funding to steer its direction in favour of its benefactors…Progress is an organisation with the funding and staffing of a minor political party, except it is operating within the Labour Party, with much of the Lambeth cabinet as members of it…” “It appears to me that the Labour council are serving two masters…There’s Progress on the one hand with its corporate sponsorship and the electorate…with the other.” “The momentum is with us, but we have to move now, particularly in Lambeth we have to move now and we have to move fast. Let’s change the face, style and substance of the politics…come together and let’s take control of our community, to shape it in our image and not in the image of Progress. If the Lambeth Council feel too tied to an outdated version of politics themselves, it’s time for us to challenge that.”

Her speech, all couched as the official view of Lambeth Momentum, was nothing short of a declaration of war on the existing Labour councillors. Those in Progress in particular were cast as traitors to the cause, serving other masters. The intent of Ellis and her colleagues to deselect them and replace them with leftist loyalists – “to shape [politics] in our image” – could not be more clear.

As she concluded, John McDonnell arrived. As one might expect, he opened with the Syria vote – saying, as he has said elsewhere, that “we were subjected to some great oratory…sometimes the greatest oratory leads us to the greatest mistakes”. That addressed, he embarked on a light-hearted tour through Corbyn’s path to power; if you can forget that you’re listening to a man who once endorsed “the bullet and the bomb” of the IRA, then it’s possible to find his self-effacing humour almost endearing: “Jeremy Corbyn is Leader of the Labour Party, and god help us I’m Shadow Chancellor.”

The power of ideological conflict to motivate and unite the Corbynites is notable – for McDonnell even media criticism from left-wing newspapers is portrayed as rightist:

“We knew the media wouldn’t give us a look in…And don’t think there’s a liberal media in this country, don’t talk to me about The Guardian [applause]…in The Guardian there was a battle going on virtually every day between left and right, and the right dominated in terms of the refusal to back Jeremy.”

To begin with, his official account of Momentum’s purpose differed markedly from Ellis’ vitriol, as he was at pains to emphasise tolerance of other views:

“Every know and then there are issues that come up…that could cause division in our party…Jeremy has always said this is going to be a new politics, and it’s going to be a kinder politics to represent his character. Er, I’m still on the course at the moment. It is about respecting other people’s view…” “We’ve rebelled more times than any other MPs…so we can’t expect now other people not to express their dissent.” “[Momentum] is not a sectarian group…it’s not about deselecting people or targeting people.”

But were those his real sentiments, or was the Shadow Chancellor simply paying lip service to tolerance within his Party? Certainly those organising the Momentum branch at which he was speaking were under the impression that this absolutely was a sectarian group, focused on deselecting people.

As so often happens, we got rather closer to the truth in the responses to audience questions.

How could there be more democracy in the Labour Party, he was asked?

“Turn up and take part…we’ve got the opportunity to turn up and transform it into a political vehicle.” “You [Momentum members] will eventually be able to ensure that the people selected represent you.”

How about those members of the Parliamentary Labour Party who voted for action in Syria?

“There is a small number [of Labour MPs] who can’t come to terms with Jeremy’s election, or a mass membership.” “Simon [Danczuk] is Simon…you just have to work with him. Eventually we’ll resolve the matter…[laughter]…I’m not saying how…[more laughter]…I’m not trying to set a hare running…in an amicable way I will convince him to my way of thinking.”

Not for nothing has John McDonnell risen to become the second most senior hard leftist in British politics. He knew exactly what he was doing. The meeting was shot through with Militant activists, Momentum was represented by a speaker who delivered a tirade targeted at other Labour factions. McDonnell carefully laid down all the cover in his speech about rejecting sectarianism within the Labour Party and denying that Momentum was intended to deselect dissenting MPs, then made sure to tell the audience with a wry smile that they were on the path to full control, they would get what they wanted and they would soon control who was selected. Had he really come to this meeting to bury factionalism, rather than to praise it, he wouldn’t have sat quietly while Ruth Cashman, in her vote of thanks, congratulated him on coming to Lambeth – “the vipers’ nest of Progress”.

As things wound down, I snuck out the back of the hall to head home. At the door, a final Stop the War activist asked me to sign his petition. “It’s against…well, it’s against Chuka, basically.”