British police are investigating claims that three women freed from a south London house were held as slaves for at least 30 years.
A 69-year-old Malaysian woman, an Irish woman aged 57, and a 30-year-old Briton were rescued from the house on 25 October this year.
The women are said to be highly traumatised and are now in safe accommodation, the BBC reports.
A man and woman, both 67, were arrested in the south London borough of Lambeth in connection with the case on Thursday morning and have since been freed on bail until January.
The suspects spent the night at a police station where they were questioned on suspicion of involvement in forced labour and domestic servitude. The couple, who are not British nationals, were arrested more than a month after police were first alerted.
Scotland Yard said it had taken a week before the women could be rescued and then further investigations had to be carried out before the arrests could be made.
Officers were contacted by Freedom Charity in October after it received a call from the 57-year-old woman, who had secretly gained access to a phone, saying she had been held against her will for decades.
There followed a number of phone conversations to the 24-hour helpine over a week, and the women eventually left the property when the owners of the house were not around, the charity said.
Police said they were not related to each other and the 30-year-old had spent her whole life in servitude. Officers are trying to establish whether she was born in the house.
Detective Inspector Kevin Hyland, from the Metropolitan Police's Human Trafficking Unit, said police had never seen anything of this magnitude before.
"We've dealt with some very traumatic cases where children have been trafficked, forced into slavery, cases where people have been held for up to 10 years.
"But this one is absolutely extraordinary and unique in that we've got people where the allegations are that they have been held in servitude or slavery for over three decades."
Mr Hyland said the women had controlled lives and spent most of it indoors, but had some freedom.
Police said the facts behind the situation were being slowly established as specialist workers were assisting the women. Officers said there was no evidence of sexual abuse.
