What makes Britons oppose immigration? 

SMALL HEATH, a pocket of Birmingham bracketed by a football stadium and a mosque, looks like a good example of integration. The high street has a mixture of halal grocers and betting shops. Since at least 1991 white Britons have made up less than half of the population. Many local people seem relaxed about immigration. “I can’t be bothered to see it as a problem,” says Freddie, a 19-year-old white builder.

Ten miles (16km) away lies the town of Tamworth. It grew rapidly after 1945 as the government prodded companies and workers to leave Birmingham. Opinions are different there. Outside a betting shop John, a white unemployed gardener in his 50s, says that “people just feel that they’ve already been driven out of their houses once.” He worries that the rapid population change in his neighbourhood will lead to people like him being ousted again.

New data analysis by The Economist helps explain why some parts of Britain, like Small Heath, are relaxed about Britain growing more ethnically diverse whereas parts like Tamworth are agitated. Several things seem to matter: the pace of change in an area’s ethnic make-up, how homogeneous it was, and how segregated it is.

The next national census will not report until 2032. So we have estimated ethnic populations by drawing on annual data on school pupils, adjusting for the fact that young people in Britain are more ethnically diverse than old people. Our estimates span a 21-year period from 2004 to 2024. They line up well with the findings of censuses in 2011 and 2021, giving us confidence in our estimates of the past few years.

We find that the share of England’s population that is white British fell from 74% in 2021 to 72% in 2024. Every large ethnic-minority group has grown (see chart 1). But some places have changed more quickly than others. The share of people in Tamworth who are not white Britons has risen from 12% to 15%, a 20% increase. Small Heath has hardly altered.

To see how places have changed, we estimate the populations of ethnic groups in 7,000 areas—each containing around 8,000 people on average—and assign each area to one of England’s 543 parliamentary constituencies. Our analysis suggests that the number of constituencies that are majority-minority (where the white British population is less than half of the total) grew from 69 in 2021 to 77 in 2024.

We assess constituencies on two indices: diversity and segregation. Diversity, which ranges from 83 out of 100 in Croydon (in suburban south London) to 12 out of 100 in Torridge and Tavistock (in Devon), measures an area’s ethnic richness. Segregation measures how evenly spread ethnic groups are across the dozen or so neighbourhoods in each constituency.

Between 2021 and 2024 all but 17 of England’s 543 constituencies became more diverse. Places that were previously homogeneous tended to change most. With few exceptions, those that have experienced no increase in diversity, such as Bethnal Green in London and Birmingham Ladywood, were already very heterogeneous.

Immigrants sometimes settle in poor inner-city areas, then move out to roomier neighbourhoods as they find their feet. But at a mosque in Small Heath, the imams suggest that immigrants are increasingly settling with relatives in suburbs and satellite towns such as Tamworth. Suburbs and small towns are changing quickly. We estimate that cities’ contribution to the national increase in diversity is nearly half what it was in the late 2000s.

Ethnic segregation is normally measured at a national scale, using census data. By that measure, England and Wales have consistently grown less segregated since the census first asked about ethnicity in 1991. Our small-area data show something different. Between 2021 and 2024 a slight majority of constituencies became more ethnically segregated (see chart 2).

In theory, the geographical spreading of minority groups ought to lead to greater acceptance. Academics have tended to find that racism diminishes as inter-ethnic contact grows. “If you think migrants are awful, having one move in next door really helps prove they’re not,” says Eric Kaufmann of the University of Buckingham.

Yet in Tamworth the tension is palpable. In 2024 a crowd attacked a hotel containing asylum-seekers there. Paul, an ex-soldier in a park on the outskirts, says that he does not agree with what the rioters said or did, but adds: “I’ll stick up for them. We were too quick to call them racist.”

When we set population changes next to people’s attitudes to immigration, as measured by the large British Election Study, we find a pattern. Constituencies that have recently diversified fastest have seen attitudes harden the most (see chart 3). City-dwellers have become a little more hostile to immigration, suburbanites and rural folk even more so.

Britain’s immigrant population has changed in the past few years, as migration from countries outside Europe has risen and some eastern Europeans have left. That adds another wrinkle. Places with the lowest initial populations of south Asian people have experienced slightly more negative shifts in attitudes towards migrants. Growth in the population of mixed-race people, who are likely to be British, has a large warming effect on attitudes.

Supporters of Reform UK, a right-wing populist party leading in the polls, have soured most on migration. If a general election were held tomorrow, 143 of the 318 constituencies that Reform would probably win according to The Economist’s election model are in the top 200 (out of 543) of England’s most segregated places.

Overall, Britain is good at assimilating immigrants and is far less racist than it used to be. But Britons do not just live in Britain. They also live in specific places, which are changing in distinctive ways. If some people grow more relaxed about immigration, and others less so, the reasons may lie in their neighbourhoods.■