'Sheds with beds' are London's modern day slums
27 February 2012 Last updated at 19:03 GMT
A series of modern day British slums have been described as "sheds with beds".
The illegal structures, some dangerous and cramped, are offered by landlords - often to Britain's illegal immigrants.
Many occupants send money back to their families in India, paying thousands of pounds to traffickers. But the economic downturn means work has dried up.
The BBC's Chris Rogers investigates, in the first of two special reports.