A modern-day slavery is flourishing in Britain, and we just avert our eyes

Nehad has the hunched look of a man who has lived with fear for years. It was to escape fear that he fled Iraq for Europe in 2003, hoping to start a new life beyond the reach of the torture and prisons of Saddam Hussein's regime in northern Iraq. But after four years of failed asylum applications in the UK, he is still living in fear.He's too nervous to tell his story inside the cafe where we meet for fear of eavesdroppers, so we sit outside. He flinches as a policewoman passes. He says he never answers a knock on his front door at home in Birmingham; friends know to call first to tell him they are coming.

He knows - as the Home Office officials remind him on his monthly required visits to sign in - that he could be deported at any time and sent back to Iraq. He could be snatched from the streets or from his bed in the middle of the night. But, as he is well aware, there is nothing unusual about his plight - he is just one individual out of an army of irregular migrants, which the Home Office estimates at more than half a million strong. They precariously exist in a kind of bureaucracy-made limbo in this country.

Deportation is not the only fear he lives with. He needs urgent kidney treatment, but an operation would require several months' convalescence. If he can't work, who will pay his rent or food? He knows his kidney malfunction is slowly getting worse. "I came here to survive, not to die slowly." He rubs tears from his cheeks.

He works in a kitchen - and he apologises for it. He knows that he's not allowed to work but explains that after his asylum appeal was refused two years ago and he was ejected from the hostel and his vouchers were stopped, he had no alternative. He got himself false papers and his employer doesn't press him for his national insurance number. The arrangement suits them both. Nehad gets £182 net for a 40-hour week, and the employer gets cheap hard labour with no sick or holiday pay. Nehad will be working through Christmas.

Nehad counts himself as one of the lucky ones. He knows someone who bought an old car for £50 just to sleep in it. Nehad rents for £100 a week, which leaves enough to pay the bills, and feed and clothe himself. He sometimes helps out other irregulars who are worse off.

"There is another, terrible life underground in this country. The government calls us illegals, but how can a human being be illegal? We are here, and we are human beings. People ask me what my hope for the future is; I don't have a right to hope, but what I would like is to hold my head up high and tell people, this is who I am."

That's what had driven Nehad to run the risk of talking to me. He needed recognition - it was the denial of dignity that had eaten into his soul, the way a whole society had decided to avert its eyes from his plight. The sheer indifference to the zombie category of "illegal" human beings our asylum bureaucracy has created.

Some irregulars have been here for years, and many will be here for years to come. They might live in your street or be sitting on the bus or train next to you and you won't know because budget clothing shops ensure that poverty and desperation is now well hidden.

The current rate of deportations is 20,000 a year. The public accounts committee has acknowledged it would take 18 years to deport all irregular migrants. That means Nehad could die of kidney disease long before his deportation order comes up, or, to put it another way, Nehad and those like him will have washed up many more of the dishes you eat off in restaurants.

And then there's the cost: £11,000 per deportation. Deporting half a million people will push the bill towards £4.7bn, according to the Institute of Public Policy Research. No one is planning to stump up that kind of money, so this is make-believe policy land: it's never going to happen.

Yet no politician is prepared to admit that, given the fevered anxieties about immigration in this country. These half a million have become a political no-go area: everyone has a vested interest in pretending they don't exist. They've provided labour for Britain's booming economy, filling the increasing personal-service job sectors of domestic work, cleaning, catering, food processing and hospitality.

In this zombie category of irregulars, you are vulnerable to every thug, every kind of criminality - and yet you can never turn to the police. You get turned away from doctor's surgeries. Your employer can deduct money from your wages, increase your hours, withhold pay and you can do nothing or he will make threatening requests for a national insurance number. Likewise, your landlord can up the rent and ignore complaints about repairs.

No one has wanted to broach the debate. Refugee organisations are too busy fighting for a fair asylum system, and trade unions, while aware of how employers can exploit irregular migrants and how that has a knock-on effect on other low-paid workers, have held back from an unpopular issue. Into this gap has stepped the Citizens Organising Foundation - representing community and faith groups in London and Birmingham - with plans to launch a campaign, Strangers into Citizens, in the new year, which will aim to open up a space to discuss this subject sensibly. It's the COF that is hunting out the rare characters like Nehad who have the courage to speak out, and have learned good enough English to tell a story that booming Britain doesn't want to hear.

There is an obvious policy option. Spain and Germany have both recently introduced regularisation schemes for long-term irregular migrants. It pays big dividends in terms of increased tax receipts as migrants start to pay tax - a billion euros in Spain in the first year and rising - which might tempt Gordon Brown. There are other advantages; any plan to successfully restrict the flow of new migrants depends on regularising irregulars. Regularisation would squeeze out those spaces in the economy that so quickly absorb and attract new migrants. But to date, advocacy of any regularisation scheme in the UK has been regarded as political suicide.

The sheer extent of this institutionalised dehumanisation makes a mockery of any pretensions to decency. While politicians fret and pontificate about policies on social cohesion and integration, this is the real question at the heart of those issues: the army of cheap labour on which our comfortable lifestyles depend.

Next year marks the second centenary of the abolition of slavery in the British empire. What makes the Strangers into Citizens campaign so challenging is that it is forcing us to acknowledge that its modern-day version is flourishing. People like Nehad may have some freedom of movement, but in reality, every detail of their daily lives is sharply circumscribed by fear. He bitterly knows that though he is 34, he has no chance of marriage, children, a home, a decent job, or a life worth living. He is just waiting - without any hope that the wait will end.

Madeleine Bunting