Sarah is due to give birth just before Christmas, but unless she can move house soon, the baby may not be coming home with her. “Our social worker has said the flat is not fit for a baby, and that the midwives are not to discharge us if we’re coming back here, she says, showing the Guardian around the one-bed flat she shares with her partner, David.

It is not hard to see why the social worker is concerned. Even before the front door opens, the smell of damp is overwhelming. In the couple’s Harry Potter-themed bedroom, the walls are wet to touch, with water running down the inside as two dehumidifiers hum away in the corner. They can’t even sleep in here any more after spores developed on their fabric headboard, and they now bed down on a mattress in the living room. Not ideal when you are eight months pregnant.

Sarah and David live on the Little London estate in Maltby, Rotherham, a colliery town that only lost its final pit in 2013. It is a curious place, built at speed during the second world war to house workers in a munitions factory who moved up from Enfield in London (hence the name). All privately owned, the flat-roofed, concrete-walled houses were never meant to be permanent, but most are still standing – just about – 80 years later.

A bunch of these “flat tops were abandoned years ago and sit, decaying, in the middle of the estate, after the London-based landlords declined to sell them to the council. Residents refer to them as “the derelicts and complain that they look as if they belong in a war zone, earning the estate the nickname Little Beirut. Even the local council leader admits they make the place look “like a bomb site.

Rent is cheap in Little London, with Sarah and David paying £400 a month for their one-bed garden flat. But many residents pay a high price with their health, complaining that the damp – caused by the naturally porous concrete walls, which soak up water from the ground, as well as the leaky flat roofs – causes them and their children serious breathing problems.

Denise McBride shows the bedroom where her two-year-old grandson, Oliver, sleeps. There are bowls of salt on the window sill, and on the little boy’s wardrobe – an economical way to draw moisture out of the air. She changes the bowls every day, when their contents are more liquid than crystal, and has resigned herself to decorating every year, tearing down one lot of mouldy wallpaper and replacing it.

These scenes may seem unerringly bleak. But the story of Little London is also one of David v Goliath defiance.

McBride, the self-described “battle axe of Little London, is a former prison worker and is leading the fightback on the estate as residents come together to demand decent living standards from their largely absentee landlords. “We are not going to stand for this any more, she says. “I won’t take no for an answer.

McBride is the chair of Big Power for Little London, a residents’ group set up this year with the help of the New Economics Foundation (NEF), a thinktank promoting “social, economic and environmental justice.

In September they launched the Little London estate assembly, a public event which encouraged residents to “be part of deciding what we need to demand from those in power.

Volunteers started knocking on doors, talking to more than 100 residents about what they would like to see improved on the estate. Two key issues came up: the damp and neglected state of the flat-tops, and the dreaded derelicts.

There are 138 homes on the estate, 88 houses and 50 flats. The biggest landlords – Rivergrove, Probex and two others with the same parent company – own 120 of them. Council records show longstanding frustrations with Rivergrove, which owns 63 homes, including 11 derelicts boarded up since at least Christmas 2015.

Big Power for Little London now meets regularly to plan its campaign. When the Guardian visits, on a grey and rainy Tuesday, the group convenes at the flat-top home of Stewart Platt, who has covered one wall of his living room with front pages of the Sun newspaper and immaculate watercolours he has painted of local scenes.

Most residents are suffering but many are frightened to raise their voices “in case they say anything the landlord can use against them, says McBride. “The fear factor is real. They can be issued with a section 21 [no-fault eviction notice]. Families get split up because there’s no council houses.

Sarah, sitting bundled up in a big coat covering her pregnant belly, pipes up: “I used to always get upset about my neighbours having to move. But since I joined this group, things are starting to get done.

Recently the group managed to raise the money to stop a family on the estate from being evicted after falling into rent arrears, and are now taking their fight to the landlords.

Around Easter this year, McBride had a knock on the door from two NEF community organisers. Heather Kennedy and Morven Oliver had heard of the problems plaguing the estate and set about empowering residents to demand change.

They were shocked at how long residents had been battling. “For decades, the landlords on Little London have been making money by renting out homes in unsafeconditions, to folks who, like the rest of us, just need a decent home to live, rest and raise their kids, says Kennedy.

McBride began to talk to other residents and, she says, “we realised we weren’t on our own. We’ve got to the point where we are all now communicating with one another and have found our leverage to deal with things.

Big Power for Little London scored a big victory recently when Rotherham’s council leader, Chris Read, accepted their invitation of a tour.

He pledged his support, emerging “surprised, disappointed and frustrated that people were living in these conditions in 2023. It certainly didn’t feel like a healthy environment for adults to be living in, let alone a baby.

Little London has been an issue for the council since before Read was elected as a Labour councillor in 2011. Following residents’ complaints in 2009, council inspectors discovered 95% of properties on the estate were not “meeting the housing health and safety rating system standard, according to Read.

The council ordered the landlords to bring the properties up to standard but met “resistance from Rivergrove, said Read. There followed years of wrangling, which resulted in Rivergrove carrying out some refurbishments.

In 2016, the council voted to buy 24 of Rivergrove’s empty homes, to refurbish and then let them out as social housing on the grounds that “the properties have been problematic for over 20 years and continue to blight the area.

The sale never went ahead because the council’s offer was “not financially viable and would not cover our costs, according to Jacob Moshe Grosskopf, a director of Rivergrove and Probex.

Rivergrove did ultimately renovate half of the derelicts, however, and they are rented out today.

The council can’t put in a compulsory purchase order now because Rivergrove recently submitted a planning application to knock down the derelicts and replace them with 15 new homes.

“If this goes ahead, great, says Read – though many residents would prefer a park on the site instead. Demolishing the derelicts would be a “good first step… because at least you’re left with a community that looks like a community rather than a bomb site.

Ultimately, Read believes Little London needs demolishing and rebuilding from scratch – an idea explored by the council in 2016 but abandoned after officers reported a “viability gap of £2.8m.

“In a fantasy world, I would like people to be living in the community that is their home, but not in those buildings. In modern, safe, warm, dry buildings on secure tenancies, he says.

“From a layman’s point of view, it’s difficult to see how those buildings are ever going to be sustainably safe, dry and warm.

Grosskopf insists that Rivergrove is a responsible landlord that has invested “hundreds of thousands of pounds … over the years to improve the living standards of the tenants. He says reported issues are “dealt with in an efficient manner and we are not aware of any long-term outstanding complaints.

He said Rivergrove’s local letting agent “works closely with Rotherham metropolitan borough council environmental health team. We have received no notices of any defects with the properties we own and continue to fulfil our maintenance obligations when either reported by tenants or noted on property inspections.

The council has begun inspecting Little London homes, says Read, though not yet any of those owned by Rivergrove. Two out of 20 so far have failed to meet legal standards. One is McBride’s: her landlord, an individual rather than a company, was given a notice to improve because of the damp and cold.

Sarah and David’s landlady – who is unconnected to Rivergrove – has given the couple heaters and says she will replace the windows. They remain on Rotherham council’s housing waiting list, hoping desperately that they will be given a warm and dry property fit for them and their baby before he or she arrives.

McBride says the residents will not give in until everyone on the estate is living in a decent home. “We’ve been ignored and neglected for so long and forgotten about. We are going to drive this until we get this place back to a decent standard, at least.

Kennedy says she will support the residents every step of the way: “The landlords on Little London need to wake up and recognise that no longer will their tenants quietly accept appalling standards, feeling powerless and alone to change things. Those days are over. People have learned the power they have when they come together.

Some names have been changed