In twenty-first century Britain, children of all ethnic groups play together at school and in their neighbourhoods. They grow up together, and have children together. The ongoing rise of the 'mixed race' population shows the extent to which the awareness of 'racial difference' has disappeared from people's everyday experience: a fact, surely, that anti-racist campaigners should celebrate.

And yet in recent years, playgrounds and classrooms have endured unprecedented interference in the form of official racist-incident reporting, training on the importance of racial etiquette, and the reinforcement of racial identities. In workplaces and public institutions, self-styled 'anti-racist' campaigns seize on bad jokes, playground insults, and clumsy behaviours as evidence that racism is on the rise, and that more rules are needed to control people's attitudes and behaviours.

How do we make sense of this reality gap, between the genuine diversity of everyday life and the racialised assumptions that drive 'anti-racist' policy? In That's Racist! Adrian Hart reflects on his experience of anti-racist campaigning in 1980s East London, and his later studies of allegedly racist behaviour among primary school children, to show how the language of anti-racism has been co-opted by a divisive new policy agenda.

In Britain today, it is no longer racism that sets us against each other, but the demand that we should be hyper-sensitive about each other's differences. As we try to navigate this new landscape, the first casualty is freedom of speech.