The English town of Boston, dubbed "the most Eastern European town in Britain" by British tabloids, has long attracted Poles to the regional agriculture industry. (Reuters)

Britain's vote to leave the European Union last week led to a near-immediate spike in reports of racist incidents. But while there is no shortage of British racism towards familiar scapegoats such as Muslims and nonwhite immigrants, two of the most notable post-Brexit events focused instead on immigrants from a predominantly white and Christian European country: Poland.

"Go home" were the words written on the Polish Social and Cultural Association's building in West London. Meanwhile in Cambridgeshire, laminated cards were distributed with the message “Leave the EU/No more Polish vermin,” written in not only English but also Polish. These two instances of anti-Polish sentiment have prompted a high-level official response from British authorities, with Prime Minister David Cameron suggesting that such behavior "must be stamped out" during a speech at Parliament on Monday. The Polish embassy in London also responded, releasing a statement that said it was "shocked and deeply concerned" by the reports.

Anti-Polish sentiment is far from new to Britain. According to figures obtained by the Guardian, in 2013, British police officers arrested at least 585 people for hate crimes against Polish people – a figure that may be a large understatement, as the newspaper was only able to get numbers from 26 of the country's 46 police forces. A survey from 2014 found that 81 percent of Polish people living in Britain had been subjected to verbal or physical abuse or knew another Polish person who had who had.

These incidents appear to have become more common as Britian's Polish population grew. There has long been a Polish community in Britain – some Polish insurgents against the Russian Empire relocated to Britain after the November Uprising of 1831, for example. Polish troops were also important allies for Britain during World War II, and after that war many were allowed to live in Britain through the Polish Resettlement Act of 1947.

But things really changed in 2004. Poland was one of 10 countries to join the E.U. that year, and Britain was one of just three member states to allow these new European citizens to work immediately in the country. Polish citizens were now part of the European principle of freedom of movement. Prompted by high unemployment and low wages at home, many young Polish citizens opted to be a part of it: About 2 million Poles have left the country since 2004. While significant numbers of the Polish citizens headed to Germany and Ireland, Britain was the intended destination for many: With an estimated headcount of 850,000, Polish citizens are the largest group of foreign citizens in the country.

A negative stereotype quickly developed in Europe of the "Polish plumber" – a foreign tradesman willing to undercut the prices of local workers. In Britain, newspapers and politicians helped spread the stereotype: The Sun once claimed that most of the population of one Polish city had moved to Britain (which prompted a threat of legal action from the city itself, angered by its negative description of the city). The United Kingdom Independence Party ran advertisements that read, "British workers are hit hard by unlimited cheap labor," though they were criticized when it turned out that the actor in the ad was an Irish immigrant.

It'd be hard to deny that there was some truth to the stereotype. There really did seem to be plenty of Polish plumbers, builders and other tradesmen in Britain not long after 2004, and they were soon followed by Romanians, Bulgarians and other new Europeans. Politicians were later forced to admit that they never predicted the huge numbers of immigrants from Eastern Europe who would travel to Britain, nor the effect that would have on some British citizens.

However, it was always a simplification. Even early on, experts argued that the arrival of Poles and other nationalities had been a boon to Britain's economy. "This influx has benefited a wide swathe of regions and industries … by increasing the flexibility of the economy and spreading the burden on housing and local services," professor Peter Spencer, chief economic adviser to the Item Club, told the Telegraph in 2006. Another study from 2014 found that migrants contributed $7 billion more to the British economy than they cost in welfare.

And as more and more Polish people lived in Britain, cultures inevitably became intertwined. British people would shop at Polish stores, eat at Polish restaurants, perhaps even marry a Polish person. Many went on vacations to places like Krakow and Warsaw. Some even chose to live in Poland: In one unusual reversal of stereotypes, there was even a British citizen living in Poland who claimed state benefits. A survey of British attitudes toward Polish immigrants from 2014 found that negative feelings were not in the majority, with 55 percent saying Poles worked hard and 52 percent saying they contributed to Britain.

Right now, it's unclear what sort of immigration relationship will continue between the two nations. While much of the rhetoric ahead of Britain's referendum on E.U. membership had hinged on immigration, "leave" campaign leaders have already begun admitting that they may not push a hard line. "We can control our own borders in a way that is not discriminatory but fair and balanced, and take the wind out of the sails of the extremists and those who would play politics with immigration," Boris Johnson said Friday.

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