My day so far: an eastern European guy picks me up in a minicab and takes me to London’s Victoria station, where more eastern European people sell me a cappuccino. Two black British men check my ticket at the barrier and a Sikh guard is on the platform. The train to Gatwick is full of foreigners.

Last month, a Ukip organiser on Humberside complained to me that “we are not even allowed to use the word foreigners any more”. Clearly that’s not true, as I’ve just used it here, but it probably wouldn’t have been my word of choice. It feels more like terminology from the past, like “labour exchange” or “wireless” used to describe a radio.

The reason it has become meaningless is that one in six British people are not white, and about one in four non-British migrants are white European.

People whose attitudes and language were formed when Britain was a white, monocultural society have lived not only through the most dramatic change in this country’s ethnic makeup. They have also lived through a parallel legislative revolution in which words, attitudes and behaviours that were normal in 1945 are now illegal.

The result, argues social geographer Gill Valentine, is the “privatisation of prejudice”. In a research project at Sheffield University [PDF], Valentine has documented a widespread resentment of the impact of equality legislation. “It’s like you’re being dictated to and controlled in what you can say and what you think,” says one woman interviewed for the study.

Such resentments are barely acknowledged in mainstream politics but may, Valentine believes, have become the invisible driver of political radicalisation on the right.

The laws referred to are indeed comprehensive. The 1997 Treaty of Amsterdam obliged EU countries to protect their citizens from racial and sexual discrimination. The Equalities Act 2010 demands equal treatment across public life regardless of age, disability, gender reassignment, marriage and civil partnership, race, religion or belief, sex, and sexual orientation.

The result has been to make language and behaviour in corporate and public space highly regulated: but in the realm of the brain, the pub, the private conversation and of course the internet – everything is possible. Valentine’s interviews reveal that people who don’t agree with equality legislation develop ways of “subverting” what they see as political correctness – and that they are particularly bitter that the workplace has become so highly regulated in terms of language and behaviour.

Put simply: there’s a liberal culture and a racist, sexist and homophobic subculture in Britain – and while we are all too aware of this on, say, Twitter, where it can be open, the place it really matters is where it can’t be properly addressed: public space and work.

Having an official culture and an unofficial subculture is not a new thing. But forcing a whole previous official ideology underground is new. When you can walk past Liverpool town hall and see statues of curly-headed black slaves carved into the stone work, you can’t be surprised that attitudes of ethnic supremacy and other imperial-era prejudices die hard.

Valentine’s findings chime with my experience as a TV reporter required to do vox pops. Over the past three years, I’ve noticed a growing tendency for people to say: “I can’t tell you what I think,” when it comes to immigration. This is not a product of increased reticence. Instead it reflects a rising awareness of – and reaction to – the legal limits to expression.

In the Sheffield research, a white man describes using subterfuge to get away with abusing Muslim women in public. He pretends to accidentally block their path, quietly insulting them and then claiming they’ve misheard: “But you’ve got to be very careful – see if security overhear, they’ll march you out … They think we should treat them as equal, and I don’t because they’re not.”

Not until you’re on the receiving end of this can you understand how prevalent it is – not just for Muslims but for many victims of prejudice – and how little the official culture of toleration has done to erode the underlying attitudes that cause it. Indeed, Valentine’s interviews show these attitudes are not the preserve of the over-60s: they are being replicated among the young.

If racist attitudes are being in effect privatised – going underground to be expressed in defiance of mainstream culture – that is the opposite of what the equality legislation intended. It turns the covert racist and homophobe into a self-styled linguistic Robin Hood. It feeds the politics of the far right with the thrill of a shared defiance that all subcultures generate.

And it puts anti-racists into a false comfort zone, where it feels like the basic arguments against prejudice no longer need to be put.

So in a tolerant society, and in corporations whose internal culture is governed by equality law, we have to find new ways to meet this challenge, beyond legislation.

Maybe the new deal should be: you – the racists and homophobes – are allowed to say what you think and we, the majority of society who are signed up to the principles of toleration, are allowed to disagree more vehemently than at present. “Celebrating diversity” is a strategy that works only when other people are not cursing it under their breath.

Maybe we should all front up and say things more clearly. Maybe NHS hospitals should advertise: “We can only run this place with ‘foreigners’ – you got a problem with that?” And maybe businesses could adopt the slogan: “We’re as black, brown, gay, straight, disabled and ‘foreign’ as Britain is, and proud of it – feel free to take your money and prejudices somewhere else.”

Instead of political correctness you would then have political honesty. It would be uglier but more real.

Paul Mason is economics editor at Channel 4 News.