A formidable coalition of businessmen, politicians, religious leaders and community workers will pledge their support tonight for an amnesty for illegal immigrants who have been resident in the UK for several years and can pass strict tests to prove their contribution to British society.
All four of London's main mayoral candidates – including, against the official policy of his party, the Tory candidate Boris Johnson – will back the campaign to offer undocumented workers the chance to be integrated into mainstream society and obtain papers allowing them to work and pay taxes legally.
In an unprecedented move that will exert even more pressure on the Government to heed calls for an amnesty, they will be joined by an array of influential figures from outside the political world, including Cardinal Cormac Murphy-O'Connor, Dr Muhammad Abdul Bari, leader of the Muslim Council of Britain and Stephen O'Brien, one of the City's leading businessmen.
"Enormous untapped potential and appalling waste is taking place right in front us," Mr O'Brien, chairman of the lobby group London First and former chief executive of Business in the Community, said yesterday. "Business leaders recognise that the case for an amnesty is both principled and pragmatic. The economic and moral case for liberating this army of workers from the underground economy is irrefutable."
The Government's tough new immigration controls have just suffered an embarrassing setback when the High Court ruled them illegal and unfair. Home Office changes to the Highly Skilled Migrants Programme (HSMP), which could lead to thousands of deportations, amounted to "conspicuous unfairness and an abuse of power", judges concluded.
Pressure to make the offer of a one-off amnesty has intensified in the wake of a campaign by London Citizens, the capital's largest community organisation. At a public assembly in Westminster tonight, more than 2,000 representatives of the city's community groups will demand the next mayor back their campaign. All four candidates, the Labour Mayor Ken Livingstone, the Liberal Democrats' Brian Paddick, the Green Party's Sian Berry and Mr Johnson, will agree.
Bishop Pat Lynch, a senior representative of Cardinal Murphy-O'Connor, said the Catholic Church backed the changes to reward immigrants who have proved their worth to British society. "We support an agreed pathway into citizenship for irregular migrants," he said. "Families like them have contributed in a number of ways to society through work, commitment to family and schools. They are settled and trying to integrate into British life." The Muslim leader Dr Bari added: "We have to find a way of helping these people become legal citizens. We are happy to accept their labour, but not grant them rights. The present situation is not just or right and we need to come to their aid."
Estimates of the number of illegal workers range from 500,000 to 700,000, half of which may be failed asylum-seekers. An estimated two-thirds of illegal migrants work in London and the South-east, in cleaning, catering, hospitality and construction. Because they do not have legal rights, their pay and conditions are subject to abrupt changes.
The Government has steadfastly refused to agree to a blanket amnesty, claiming it would lead to a vast increase in the number of immigrants arriving. Liam Byrne, the Immigration minister, reaffirmed the Government's commitment to clampdown on businesses employing workers without full legal rights.
But critics say granting deserving candidates an amnesty would be ethically and financially sound. A report by the Institute for Public Policy Research concludes that allowing illegal immigrants to work legally and pay taxes could yield a windfall of between £1bn and £3.3bn.
Last month Mr Livingstone called for a "fresh start", with a one-off amnesty for migrants without "regular status", in spite of his party's stance. "Migrants contribute hugely to the economic, civic and cultural life of London and the UK," he said. "To have a substantial number of them living here without regular status because of deep-rooted failings in the immigration system, some dating back over a decade, is deeply damaging to London as well as to them."
London Citizens' proposals demand undocumented workers meet strict criteria before obtaining full legal privileges. These include proof of their residence in the UK for at least four years, no significant criminal record, and a willingness to learn English. If individuals met these criteria, they would be placed on a two-year path to citizenship, after which they would have to have a favourable reference from an employer or a community leader.
The Liberal Democrats are the only party committed to the idea of an "earned path to citizenship". The Tory leader, David Cameron, distanced himself from an amnesty, saying: "Boris is his own man. He is standing on his own platform and he dictates his own policies."
In the High Court, Sir George Newman said there was no reason why migrants who had come to Britain in 2002 under the HSMP should be deported for failing to accrue the requisite number of points. But Mr Byrne said he would appeal against the ruling.