Licensing raids reveal overcrowded homes and bed bugs
10 September 2013 Last updated at 00:30 BST
Council officers have been enforcing licensing rules which aim to curb the number of overcrowded houses where landlords have split homes aimed at one family into flats for many more people.
They are gathering evidence before they take action against the landlords, and police accompanying them have found people who have overstayed their visa in a series of early morning raids.
The Daily Politics' Giles Dilnot went along to a raid in Newham, east London - with senior private sector housing officer Julia Bull - where one landlord was making £50,000 a year letting out "unlicensed, unsafe and unpleasant" properties.