It was an unusually heavy response to a fight in a school canteen: a police helicopter, police dog and 15 police vehicles all rushed to Fir Vale Academy in Page Hall, Sheffield, one Tuesday in late September.

The drama, inevitably, was caught on camera. The screaming in the dinner hall, children climbing on tables to escape. Outside, a teenage girl in handcuffs, face-down on a police car; the man in a tracksuit being mauled by a police dog. A pupil had texted false talk of a knife fight, and parents had been trying to scale the fence to reach the school.

Eighty miles away in Liverpool, Gill Furniss made plans to leave the Labour party conference, missing Jeremy Corbyn’s speech. As the local MP, she could see that the fight had the potential to reignite long-running tensions in Page Hall – especially if, as chatter at the school gate suggested, the fight had begun when a Roma girl pulled off the headscarf of a Muslim classmate. “I always keep an eye on Page Hall,” said Furniss. “Clearly something had happened that led parents to become extremely worried about what was going on.”

Five years ago, David Blunkett, serving his final years as an MP, warned that Page Hall, a multicultural district of Sheffield which had become one of the city’s most deprived areas after the decline of the steel industry, was a “boiling pot” waiting to spill over. Describing tensions between the more established Pakistani community and an influx of Slovakian Roma people, whom he said needed to make more of an effort to fit in, he told BBC Radio Sheffield: “We have to change the behaviour and the culture of the incoming community, the Roma community, because there’s going to be an explosion otherwise. We all know that.” Blunkett feared a repeat of violence that erupted between Asian and white youths in Bradford and other cities in 2001.

Three Roma – Miroslava, Naci and Jurej Nacko – help collect litter from the park in Eastwood, Rotherham. Photograph: Gary Calton/The Observer

Though they wouldn’t say so publicly, officials from communities all over the country with a sudden high concentration of Roma residents recognised the tensions Blunkett described. In Rotherham, Doncaster, Derby, Peterborough, Glasgow and Luton, the local authorities continue to grapple with the challenges brought by their new Roma residents since EU expansion into eastern Europe in the 2000s. Many fear that Brexit will result in the loss of funding from the EU through the European Social Fund, undoing any progress that has been made.

The last, most scientific, attempt at estimating the UK’s Roma population, by Salford University in 2013, put it at just under 200,000. That has almost certainly ballooned. As EU citizens, mostly from Slovakia, the Czech Republic, Poland, Hungary and Romania, Roma do not have to register on arrival. So local authorities tried to make their own estimates based on school admissions and GP registrations – neither terribly reliable considering the Roma mistrust of authority, stemming from deep-rooted discrimination in their home countries.

Like many new arrivals, the Roma have tended to stick together. They rent poor-quality private accommodation in the cheapest areas and toil in the sort of unskilled, low-paid jobs many Britons snub. Big families cram into two-bed terraced houses.

In many rapidly changing neighbourhoods, tensions over noise, antisocial behaviour and litter quickly surfaced with the more established residents. Usually of immigrant background themselves, many of them had worked in the same minimum-wage jobs on arrival as the Roma but had managed to buy their properties. The flow of Roma has slowed since the Brexit vote brought an increase in hate crime, but in a letter to parents after the canteen fight at Fir Vale, the soon-to-be-ousted headteacher said 24 new pupils had started in the week after the incident.

Six miles north-east of Page Hall is Eastwood, a suburb of Rotherham. Ever since she was elected to represent the town in 2012, Sarah Champion MP has been receiving complaints about litter, fly-tipping and antisocial behaviour, blamed on Roma arrivals. For a long time, the complaints came from white British and British Pakistani people who had bought their homes before EU enlargement, said the Labour MP. “There are people who put all their savings into their homes and find how they are worth less than they paid for them. They are stuck. They can’t leave the area. It’s a nightmare,” she said. A two-bed terrace on Milton Road, one of the most fly-tipped streets, sold in 2015 for £38,000. Four years previously it had been bought for £59,950.

Most recently, postal workers said they were so frightened delivering in Eastwood after being mugged for their parcels that they no longer went out alone. “They are terrified because of the level of intimidation,’” said Champion. She went out on a round with two postal workers: “If I wasn’t with two post people, I would have been running away. I was really shocked how bad it was.”

But as their English improves, the Roma want to defend themselves. Recently, Champion went to a meeting of about 40 Eastwood Roma residents, who said they felt intimidated and victimised in their own homes, let alone the streets. “They talked of bullying and degradation, and they were saying that it was the Pakistanis who were doing it,” said the MP. She said the “disreputable” landlords renting to Roma were almost exclusively Pakistanis, happy to take high rents for substandard properties, secure that the Roma would not complain.

Four Roma children – Nikolas Macko, Jurej Nacko, Sophia Slepcikova and her brother Dusan Slepcik – were among those who photographed the park in Eastwood, Rotherham, to suggest improvements. Photograph: Gary Calton/The Observer

Back in Page Hall after the fight at Fir Vale Academy, trouble was brewing. The authorities refused to answer questions about what had caused the fight, but multiple sources have told the Observer it began when a Roma girl pulled off the headscarf of a Yemeni classmate. It was not the first such incident: one father said he was called in to school at the start of term after his Year 7 daughter had her hijab “ripped off” by another Roma pupil.

Sensing trouble, the school cancelled an open meeting to discuss the incident. So a Neighbourhood Watch meeting in nearby St Cuthbert’s church hall was hijacked instead. Angry Fir Vale parents – most Pakistanis, no Roma – shouted at a panel of wincing white council workers about “them”. Their new Roma neighbours. “David Blunkett was right!” yelled one man. “This is a ticking time bomb. If it goes off, you’re going to need the army.”

They refused to see the hijab incident as an isolated scrap between teenage girls. “This is not just a school issue… This is ready to blow up. Bang,” warned one man. “We’ve lived here 35, 40 years and you expect us to sit silently,” said another, claiming that he had 60 cousins ready to provide back-up for what he said could be “a riot like you’ve never seen before in your life”. None of them wanted their names published.

In Rotherham last week, the Observer met a small group of young Roma women at the Clifton Learning Partnership, which helps Roma settle into UK life. Like their compatriots in Page Hall, they are fed up with being blamed for every piece of litter on Eastwood’s streets, every dumped mattress, every late-night party. “It’s all our fault, all Roma fault, like always, everywhere,” despaired one 27-year-old, who came to Eastwood nine years ago and didn’t want to be named.

“Because we live here, where there is a big population of Roma, they say we are doing all this mess… All other communities are perfectly brilliant,” she said, with deep sarcasm. She said she often saw vans full of furniture and trade waste drive into Eastwood, dumping it on the pavement.

In Page Hall, where streets are regularly littered with sofas, mattresses and building waste, the council recently caught “a serial offender from outside the area”, according to Colin Havard. He leads an £835,000 Home Office-funded project from the Controlling Migration Fund to help communities “experiencing high and unexpected volumes of immigration to ease pressures on local services”.

Mattresses dumped in Page Hall. Photograph: Gary Calton/The Observer

Part of the money has been used to fund three street wardens with powers to issue fixed penalty fines, as well as to identify and address antisocial behaviour. Of 51 littering fines issued since May, not all the culprits have been Roma. “They have included all sorts of people, including staff from the school, so not just Roma people, as lots of people are capable of dropping a cigarette butt or a crisp packet,” said Havard.

In Page Hall last week a white couple stopped the passing enforcement officer to demand action over graffiti that had been scrawled on the side of their house while they were on holiday, reading “Mizigarovci [a Slovakian Roma surname] are the bosses”.

Back in Eastwood on Friday, a group of Roma went out litter picking in the community, insisting they were not to blame for the mess. They blamed landlords, who don’t want the hassle of going to the tip or paying the council £27 to pick up bulky items and tell tenants to leave what they don’t want on the street.

Two years ago Rotherham council started to pay a street cleaner to litter pick in Eastwood from 6am to 2pm, five days a week. “When I leave, it’s spotless. The next day it looks a mess,” she said. So much furniture was dumped each weekend that it was “like MFI on a Monday”, she said.

Many authorities have tried to employ Roma to explain everything from the vagaries of the local recycling system to the importance of childhood inoculations, but it has proved difficult, said Havard. “We have an example of a school where they had to have the right Roma person. They had a Roma person who was from the wrong village and none of the kids were listening. They then had a different Roma person who was from the right village and, all of a sudden, the kids are starting to listen to what he is saying, because he has the status in their community,” he told MPs last week.

MP Kate Green, co-chair of the All Party Parliamentary Group for Gypsies, Travellers and Roma, accuses the government of “consistently” overlooking the Roma community. She worries that the resources necessary to tackle the inequalities Roma experience will be even harder to come by, post-Brexit, as groups and schemes supporting marginalised communities lose funding they have been receiving from the EU through the European Social Fund. “The most pressing issue is the creation of the new settled status after Brexit,” she wrote in a recent report. “The government has shown little interest in the difficulties marginalised groups may face in obtaining the information and evidence needed to apply for settled status. As a result, some will simply stay without it, unrecorded, under the radar, and even more vulnerable.”

On Monday a new headteacher starts at Fir Vale Academy. The last head departed two weeks ago “by mutual agreement” with the governors. One of them, Richard Edwards, a former master cutler, wrote an article in the Sheffield Star urging a focus on community cohesion. “No one will disagree that in Page Hall there are pockets of poverty, different communities need to reach out to each other, but a coordinated agency response is needed which is currently sadly lacking. Perhaps the real story here is a focus on the community being let down by many so-called support organisations, many with taxpayer funding, which appear to be inactive,” he wrote. “The school reflects the community it serves; that community has a lot of underlying tensions. What the whole community needs is something to unify it, not divide it further.”