BOSTON, United Kingdom -- Karol Sokolowski looks on as his mother-in-law, Sylwia, attends to steaming pans of goulash, beans, and Polish dill-pickle soup.

It's almost lunchtime at Swojskie Jadlo -- which translates roughly as A Taste Of Home -- the restaurant they opened two years ago to cater to a mostly Polish clientele in the market town of Boston, east England.

Sokolowski, a 30-year-old native of Starachowice, a similarly sized town equidistant from Warsaw and Krakow, insists his future is in the United Kingdom.

"I feel at home here," he says. "It's not a very pretty town. You have to say that. It's an ugly town. But I feel at home. We have rented a nice house with a nice garden. And when [I go] to Poland for a holiday, I start to miss my home, [which] is here."

Like thousands of other Poles, Lithuanians, and Latvians, Sokolowski's family was initially drawn to the area by jobs at Lincolnshire's farms and food-packing factories after 10 new countries joined the EU in 2004. Here in Boston, nearly 11 percent of the town's 65,000 population now hails from the "newer" EU states, the biggest proportion anywhere in the U.K. It's a surge that has cheered local agricultural businesses, but also led to tensions with locals.

At a national level, too, immigration has become a central and divisive issue ahead of Britain's June 23 referendum on whether it should remain a member of the bloc. Those arguing that Britain should leave say Europeanwide rules guaranteeing freedom of movement have led to net immigration levels that are too high -- some 184,000 EU nationals a year -- and put a strain on public services. A new poll shows immigration has overtaken the economy as the issue most likely to sway voters -- a boost to the "leave" campaign, which sees immigration as its trump card.

'We're Full Up!'

"We used to have such a quaint town and it's not a quaint town anymore," says Janet Ashberry, a retired textile factory worker walking near Boston's market square and 14th-century church, St. Botolph's. "I'm not against them, but it's the amount. We're too full. The health service can't cope. The schools can't cope."

For Angie Cook, the owner of a refrigerated-transport business, it's personal. Cook says a local competitor put her out of business several years back by hiring drivers from newer EU members and paying them a pittance.

"It was either not make a profit or cut [my] drivers' wages," she says.

Cook's list of complaints doesn't end there. Driving down the town's West Street -- locals now call it "East Street" -- Cook points out its many Polish and Lithuanian food shops and bars and says it's become a "no-go area" for English people on weekend nights.

She cites higher instances of crime, drunk-driving, and nuisance drinking in the town. Interpreter costs have put a drain on the health service, she says. And rents are higher as landlords squeeze multiple migrant workers into single-family homes.

"We're absolutely full in Boston," says Cook. "There's no housing. There's nowhere for any of them to live. That's why they're putting them in caravans. But then it's having an adverse effect on English people who have been born and bred here, lived here all their lives."

'Narrow-Mindedness'

But others say the newcomers -- generally younger and more economically active than the local population, according to a Lincolnshire County Council report -- have been a shot in the arm for Boston, which gave its name to the rather more famous U.S. city in the 1600s.

"This town would be dying on its feet if there wasn't that European community here," says public-sector worker Josh Abrams.

"There's a lot of narrow-mindedness," Abrams says. People "might have had a one-off bad experience and they paint everybody with the same brush. It's always the minority [being blamed] -- 'Foreigners are always drunk on the street.' But there are dozens of English people every Friday night, Saturday night drunk on the street."

And for some, the benefits are even more tangible.

On a weekday morning, a small group of workers is busy hoeing weeds on Robin Buck's celeriac field a few miles south of Boston.

Buck, who farms 650 hectares of vegetables and flowers, calls a Boston agency each day to send him the number of workers he needs. Today they sent seven. During daffodil-cropping season, he might hire 200.

"We crop 4 million bunches of daffodils, most of which go abroad to Europe," Buck says. "And we couldn't do that without the availability of people from, in our case, Lithuania and Latvia."

Not that long ago, he says, the seasonal workers were Irish. Then they were locals. For a time, as England's industrial north went into decline, people would come from Sheffield and Doncaster to pick vegetables. And now it's the turn of workers from newer EU member states.

"English people just don't want to do it now," Buck says.

Pierogi Power

The "Vote Leave" campaign says that in the event of a so-called Brexit, Britain will end the automatic right of EU citizens to come and live in the U.K. Instead, they propose a "points-based" system that would allow in people according to their skill levels. But they say there would be no change for EU nationals currently legally in the U.K.

So a Brexit is not likely to affect Vytautas Cesnavicius, a Lithuanian factory worker who came to Boston three years ago.

"English people don't want to work for 7.20 pounds ($10.30) an hour," the living wage, he says. "So if everyone went home to Lithuania, Latvia, Poland, it would be a big problem for Great Britain."

None of the EU nationals interviewed in Boston say they have personally experienced any hostility from locals, though a couple says they have heard of it happening to others. Some even express understanding for locals' anxiety.

Sokolowski says it would be "the end of the story" if EU rules were revised so that the U.K. or other countries could better control who came in. And Jurate Matulioniene, who teaches English to adults and Lithuanian to children, says it would be reasonable to set limits.

"This great scale of migration [has an influence] on native people, on their identity," she says. "It should be -- maybe not stopped, but some laws should be set and maybe it should be a selection, like in other countries."

Brexit or no Brexit, Sara Aifa strikes a note of optimism about the future. The Polish native, who just turned 18, will be voting for the first time on June 23 -- to stay "in."

"I've been to pick my sister up from school the other day and this little boy said, 'I know some Polish!' And he said a sentence," Aifa says. "So I think these little children are more open-minded than the older ones. They're living with immigrants, living everyday life learning other languages, learning other cultures. People know what pierogi are now. People are more open minded."