ITV News has obtained figures that show councils in London have made a total of just six prosecutions for overcrowding in rental properties in the last five years.
Our Freedom of Information request found:
Just six landlords have been prosecuted for overcrowding in the last five years.
In one case a landlord was fined just £175.
Many councils told us they need more powers.
And one - Haringey Council - said it simply doesn't have the resources to check up on properties it's identified as overcrowded.
By law, landlords can be prosecuted for renting out overcrowded homes, but councils say the law is unenforceable and they need more powers and resources to check on properties they've identified as overcrowded.
ITV News report Ria Chatterjee was out on an enforcement raid at dawn in Brent.
Enforcement officer Herb McGowan outlined some of the fire safety issues that were found at one property.
There are some serious fire safety issues here that have to be resolved and we will be taking robust action to ensure this is dealt with. It is grossly unsafe for this to occur.
"If you rent a house you are supposed to offer some standards," resident Irina Bilal told ITV News.