Momentum activists could have a significant impact on the doorsteps of north London ahead of May’s election. We asked activists from four north London boroughs how socialism is bedding in.

Momentum’s membership now exceeds 40,000, bolstered by 1,000 sign-ups in the first two weeks of April.

The grassroots left-wing group was founded two and a half years ago from the remains of the campaign to get Jeremy Corbyn elected Labour leader. It now has more paid-up members than the Green Party and claims it’s catching up with the Tories.

Momentum considers Islington relatively secure with 561 members – a confidence underpinned by the commanding majorities of Labour leader Jeremy Corbyn (60.5 per cent) and shadow foreign secretary Emily Thornberry (62.8pc) who represent Islington North and South respectively.

CLP member Andrew Berry has served on Unison’s National Labour Link Committee since 2013 and is now standing for one of four annual south-east positions up for grabs on Momentum’s National Coordinating Group. He’s up against big names such as the incumbent Jon Lansman, who founded Momentum and also sits on Labour’s NEC.

Andrew said Islington Momentum sends its members across borough borders to campaign in target seats like Wandsworth as well as campaigning more locally.

He told this newspaper: “In Islington there has been a long history of the left, and Momentum’s a supplement to it. It’s about bringing in the new members and catching them up with the rest of the local party because grassroots activists are already there.”

Asked why he was running for the NCG, he said: “Christine Shawcroft, who was on the NEC, said we should disaffiliate from the trade unions on Facebook and it went everywhere.

“I think she’d had a bad day. There was a lot of disquiet from trade unions. My main motivation for standing in the NCG election was to make a point that Momentum needs to make links with trade unions and keep them involved.”

Across the border, Hackney – with 690 members – has the highest Momentum headcount of the boroughs we researched.

Heather Mendick was the engagement officer for Hackney Momentum until 2017, when she was elected secretary for Hackney South Labour. But, shortly afterwards, she rescinded her Momentum membership.

She left because of her demanding workload but also said she didn’t agree with how the group’s national constitution was being enforced by those at the top.

Heather explained: “You’ve got to remember this is a super young movement.

“Even when there are differences the solidarity in Hackney is amazing. People work together and support each other here in a way I don’t think I’ve ever known in my lifetime.”

Like Andrew, Ripon Ray from Hackney Momentum is standing for one of the NCG south-east positions.

“I think there is a dangerous potential that Momentum could retract itself from the grassroots,” he said. “We need to show we’re not just here to focus on the Labour Party but really build something on the ground and attract more membership.”

A couple of clicks to the west is Camden, where Momentum’s roll call is a respectable 445. But a local member, who asked to remain anonymous, told us the right of the party had tried to stop left-wing candidates from running for election.

Those on the left who did apply to run on May 3 failed at the first round, they said, and had to go through appeals to get onto the ballot paper. When those were successful they found themselves dumped in safe Tory seats.

“Look at the manifesto,” the source added. “It’s an anti-austerity manifesto but not a Momentum manifesto. It’s not a manifesto that says we want to stop or scale back public partnerships. It’s not a manifesto that says we won’t sell off council land to private developers. It’s not radical left at all.

“We do have a group of people in Camden who are enthusiastic about socialism and behind the leader – it’s just hard to have a voice in local politics when all the positions of power are controlled by the right.”

The member told us a key point of difference within Camden Labour was the Public Investment Programme (PIP), a 15-year scheme of council-funded regeneration many on the left consider to be a watered down Haringey Development Vehicle.

Camden Labour has endorsed the PIP as a way to invest in the community against a backdrop of central government cuts.

Haringey Momentum, with 565 members, has received more media scrutiny than any other branch in London.

The battle between left and right-wing of factions in Haringey Labour has been well documented. It centred around the now notorious Haringey Development Vehicle, a 50/50 public-private redevelopment initiative that critics labelled social cleansing.

The furore over these plans and an lack alleged lack of transparency resulted in multiple councillors being deselected by their local branches, and saw Haringey Council leader Claire Kober step down.

Haringey Labour recently published its manifesto for the local elections, which reaffirms its opposition to HDV.

Cllr Kober had said it was Momentum activists who had made the HDV unpopular.

The current leader and her supporters believe the group are eyeing up the council as the first “Momentum Council”, triggering comparisons with Militant running Liverpool Council in the 1980s.

But deputy leader Jo Ejiofor, tipped to replace Cllr Kober if Labour takes the town hall, said: “Momentum is now part of the Labour Party, like the Co-op, trade unions, and groups like Progress.

“All these parts of Labour have their own views and aspirations for how Labour should deliver for the people we represent.

“But let me be clear; there is no such thing as a Momentum councillors on Haringey Council, only Labour councillors.”