One of those was Jackie, who told the BBC she used to be a heroin and cocaine addict.
Her dealer allowed her to run up a large drug debt. When she could not pay it back, he added an extra £2,000 to the bill and said she had to have a dealer living with her until she could repay the money.
She said she was cuckooed for months, and became “a prisoner in my own home”.
“I asked him to leave so many times and he said: ‘My guy said I’ve got to stay here'”.
“It just meant that I had to stay in one room. I tried to get access to the front room and the kitchen and he just went, ‘no, you’re not coming in’. I had to stay in my bedroom. Occasionally he might say ‘I’ll buy you chicken and chips or something’ but it was very rare,” she said. She said she used drugs to get through the ordeal.
After several months of occupying the property, the dealer finally left. Jackie said suspicion of police watching him made him leave.
She is now free from drugs after going to rehab, and works with various support groups to raise awareness of cuckooing and how it can happen to anybody.
“It’s not just about drugs. It can be about anything. It can be partners [not leaving]. It can be family members. It can be anybody that refuses to leave your property and it can be used for all sorts, money, stolen goods, anything they think they can exploit you”, she said.
When the BBC visited the London properties with the Met police, officers said squalid conditions were the norm when it comes to cuckooed premises.