and it's not just illegal immigrants, it's a precedent that any data a homeless person gives to a charity (or indeed, any information anyone gives to any charity) may eventually find it's way into the hands of the government to be used against them.
Martha Spurrier, director of Liberty, said: “Vulnerable foreigners have been systematically targeted by a government obsessed with deportation, whatever the human cost. Children have been kept away from schools. Pregnant women and others in need of medical help are avoiding seeking it.
“Now even people forced to sleep on the streets will be frightened to seek support. Who knows where else the Home Office’s poisonous tentacles have reached? There is a crisis of compassion in our political system and it needs to be exposed and undone. The government must come clean and end these secret deals – or we will look to challenge them in court.”
basically this. but maybe they don't deserve medical care in the first place? a controversial subject!