With the first census figures arriving today, we can expect a slew of alarmist stories about the dire demographic and social consequences of immigration. Many of these stories will cite public opinion surveys showing that the majority of British voters hold negative views about migration, and want it reduced. When asked about overall immigration in the abstract, this is certainly true. But dig a little deeper and a much more nuanced picture emerges.

For example, who is an immigrant? Immigration Minister Damien Green has repeatedly argued that excluding students from immigration statistics would be "absurd" because under international definitions students who come here for more than 12 months count as migrants. But voters don't think in terms of international definitions. And when the Oxford Migration Observatory asked people who they thought of when asked about migrants, less than three in ten named student migrants, who constitute the largest group of migrants in official statistics (37% of the total). Asylum seekers, who constitute only 4% of Britain's migrant inflow, loom much larger in the public mind: 62% of voters said they had asylum seekers in mind when asked about immigrants.

Voters also hold more nuanced views about migrants than they are often given credit for. Initial scepticism about migrants often melts away when they see clear social or economic benefits. Although the British are more negative about immigration in general than those in other large European countries, majorities of voters are supportive of admitting more highly qualified migrants; more doctors for the NHS and more care workers to support the social care system.

The British are also more socially polarised over immigration than our European neighbours. Age, education, economic security and ethnic background are all very strong predictors of perceptions about migration. And all of these factors overlap, producing a "generation gap" over immigration: older, less educated voters who grew up in a more homogenous, less mobile society are profoundly sceptical about immigration, and regard it as an urgent problem. Younger, more educated voters, growing up in a diverse society where mobility across borders is taken for granted, are much more positive, on practically any measure. This generational polarisation also shows up in other areas such as racial attitudes and national identity beliefs. It shows up also in the willingness of voters to discriminate between white and non-white migrants: older Britons discriminate strongly against non-white migrants, but their grandchildren are much less likely to do so.

This brings us to an important point: the immigration debate is not being carried out in a vacuum, but is part of a much broader set of issues concerning identity and diversity. Many of those who are most anxious about immigration view it as one symptom of a broader shift they oppose: the gradual move to a diverse, multi-cultural Britain. Although politicians focus on the economic impacts of migration, the impacts on culture and identity are as important for voters, if not more so: such anxieties were at the core of the BNP's electoral appeal for many voters in the 2000s. These concerns are real, but they are also concentrated in the cohorts of voters who grew up before the first wave of mass migration in the 1960s began to change the face of Britain, and who perceive the change as threatening the Britain they remember. Those who have grown up since migration began have no recollection of a homogenous British society, and are much more comfortable with the diversity they regard as a part of everyday life.

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