In retrospect, the signs – at least some of them – were there. The three-storey council block on the Angell Town estate in Stockwell, south London, is tidy and well-kept, but neighbours say that the opaque net curtains were permanently drawn.
Members of the local community say the estate is a friendly place to live. Many of the blocks overlook each other, and people say they know everybody by face if not by name. But the residents of this particular house – a couple of Indian and Tanzanian origin, both aged 67, and three women aged 69, 57 and 30 – stood out because they were so reclusive.
"I thought the elderly couple were looking after the others, as if they were carers," said a resident who did not want to be named. "But there was something strange about it all. The older couple were definitely the ones in charge. They were the dominant ones, you could tell that."
They were not sexually abused, but the three were regularly beaten and subjected to profound emotional abuse. The youngest, a British citizen, has spent her entire life in captivity. The other two are Irish and Malaysian.
Following a succession of secret telephone conversations with the Irish woman, representatives of a charity called Freedom mounted a rescue attempt, supported by the Metropolitan Police's Anti-Human Trafficking Unit.
At an agreed time, the Irish and British women managed to walk out of the house. They were met by charity representatives and taken to safety. A short time later, the rescuers returned for the Malaysian.
Such is the influence the captors had exerted over the three women that the victims agreed to escape only on condition that the police would not take any action against their captors.
Over time, however, the police "[worked] to gain their trust and evidence". On Thursday – four weeks after the women had escaped – the "heads of the family" were arrested in a dawn raid with "no confrontation". The couple stand accused of assault and false imprisonment, and also face immigration charges.
Police have confirmed that the suspects, who were unaware of the escape, had not reported the three women missing in the four weeks prior to their arrest. Intriguingly, the police have also revealed that the suspects had been arrested in the Seventies, though no further details have been released.
One of the most mystifying aspects of the case was how these women could possibly have been held captive for so long without the use of physical constraints, bound only by what Commander Steve Rodhouse of the Metropolitan Police called "invisible handcuffs".
However, it emerged last night that the origins of the relationship between the captors and victims lie in a "collective" of the Sixties. According to Commander Rodhouse, the 67-year-old couple met the two older women after coming to Britain in the Sixties.
They were drawn together by a "shared political ideology" and lived together at "an address that you could effectively call a 'collective'."
"Somehow that collective came to an end and the women ended up continuing to live with the suspects," said Commander Rodhouse.
Dr Suzanne Newcombe, a research officer at Inform, a research unit specialising in cults and New Religious Movements at the London School of Economics, is not surprised that the 30-year incarceration may have its roots in a cult-like organisation.
"Ideological beliefs of any sort can have an incredibly powerful effect on how people behave," she says.
According to Professor Rod Dubrow-Marshall – a social psychologist and expert in cults – London was "an extreme hotbed of political and religious ideology" during the Sixties. "There was a whole mixture of spiritual and far Left political ideology," he said.
"New groups would take ideas from established political and religious doctrines and create a toxic mix of their own, and leaders would claim to have special insight or powers that would allow followers to reach a sort of promised land."
Built into the ideology of many of these groups were mechanisms of mind control. Followers of both political and religious leaders were made to believe that breaking away from the group would have catastrophic consequences.
Moreover, according to Professor Dubrow-Marshall, they were often required to perform menial tasks "24 hours a day, seven days a week" as an "act of political or divine work". The parallels to this case are all too obvious.
"Many devotees may have had a genuine attachment to the leader initially," he says. "They would grow to admire him and wish to demonstrate that by operating essentially as a slave to that person.
"Sometimes it fades over time... they gradually began to question if they are doing the right thing.
"Where the ideology is very powerful and people have really committed to it, even when the group disappears they continue to work towards their overall spiritual goals... It can take decades before they are free from those psychological bonds."
Doubts may have been growing in the women's minds over a long period of time. The catalyst for action was a television programme, believed to be Forced to Marry, which was broadcast in October as part of ITV's Exposure series. The Irishwoman, moved by the documentary, memorised the telephone number for the Freedom Charity, which was featured on the programme, and called the number in secret.
Even after this first spark of recognition, however, the cultish brainwashing was so effective that it took the charity workers a great deal of effort to break through.
"The woman quickly started to have second thoughts," recalls Aneeta Prem of Freedom, who played a key role in speaking to the woman.
"We had to persuade her that the outside world could hold something much better than she would ever experience in captivity.
"We only spoke a few times, but it was very intense," she says. "When I met the three ladies... they threw their arms around me and we all started crying. They said individually: 'Thank you for saving our lives.' It was very highly charged and emotional."