Social workers were aware for some time of the dysfunctional "family" where three women were allegedly kept as slaves.

On Saturday police began door-to-door inquiries in Brixton, south London, where a 67-year-old man and woman, of Indian and Tanzanian origin, were arrested on Thursday. They are suspected of keeping the women in a state of domestic servitude. Police said that emotional and physical abuse appeared to have "been a feature" of all the victims' lives.

A local source claimed that at least one of the women had attempted to escape and that local authorities had been involved with the household. The "cult-like" nature of the relationship between the women and their alleged jailers meant that the victims had apparently previously vetoed any action being taken, making it almost impossible for the authorities to intervene. But there were thought to have been "explosions" of violence within the house, which at one time had six people living there.

The three women allegedly kept as slaves – a 69-year-old Malaysian, a 57-year-old Irish woman and a 30-year-old Briton – were helped to escape from the house in an area of social deprivation in Lambeth, south London, by charity workers and police on 25 October. They had allegedly been held against their will since the eldest two first joined what police called "a collective", organised around a shared political ideology, more than 35 years ago. The Met have already said that the older couple had been previously arrested in the 1970s, but have not elaborated further.

Police on Saturday gave further details about the chain of events that led to the arrests. Commander Steve Rodhouse said that the women had been living in so much fear that they had only left the property on the condition that officers did not arrest their alleged captors.

"Part of the agreement on 25 October when they were removed from the suspects' address was that police would not at that stage take any action. Since that date we have been working to gain their trust and evidence: that came to fruition on 21 November when we were in a position to make arrests," he said.

He said the three women had not been reported missing since they had left the house, and described the case, which currently has at least 37 officers working on it, as "highly complex and difficult".

"The suspects are of Indian and Tanzanian origin and came to the UK in the 1960s. We believe that two of the victims met the male suspect in London through a shared political ideology. The people involved, the nature of the collective and how it operated is all subject to our investigation and we are slowly and painstakingly piecing together more information. Somehow that collective came to an end, and the women ended up continuing to live with the suspects. How this resulted in the women living in this way for over 30 years is what we are seeking to establish, but we believe emotional and physical abuse has been a feature of all the victims' lives."

The 30-year-old woman had never been to school and had lived with the 67-year-old couple all her life, he said. Police have not confirmed the relationship of the younger women to the other adults, but sources have suggested she was the daughter of the Irish woman. The head of the household, reportedly a dominant and powerful character, is said to be her father.

"The 30-year-old woman does have a birth certificate; however, that is all the official documentation we can find," said Rodhouse. "We believe she has lived with the suspects and the other victims all her life but, of course, at this early stage we are still seeking out evidence. I understand the huge public interest in this case, the desire for information and the shock that it has caused."

The MP for the area, Tessa Jowell, said she had been briefed by the Met on the case and that it had raised a lot of questions. "I don't think it is a fair representation to call it a cult. Cult-like perhaps, but what will come out over the next few weeks is the sheer complexity of this situation," she said. "This was a bizarre household, a unique and very unusual story, but the coercion and fear is no different from that of so many vulnerable women who can't leave abusive relationships because of fear, dependency and terrible abuse that becomes normalised."

Jowell praised the Freedom Charity, which helped the women's escape. "They have done an extraordinary job. Like so many small charities working day in and day out to help victims of slavery and trafficking and other forms of abuse, they develop enormous expertise and make an enormous contribution."

The founder of the Freedom Charity, the small organisation run by two sisters which worked to extract the women from the house after the Irish woman called their offices, said the publicity had resulted in an unprecedented number of cases of domestic slavery being reported to them.

Aneeta Prem said: "We have seen an extraordinary rise in calls to our helpline since the rescue of the three women came into the public domain. We received five times as many calls in 24 hours as we normally do in one week and are needing to increase our resources to cope with this extra demand.

"These women have had traumatic and disturbing experiences, which they have revealed to us. What needs to happen now is that the three victims, who have begun a long process of recovery, are able to go through their rehabilitation undisturbed, without being identified."

• This article was amended on 17 November 2013 to remove a reference to social services being aware of the women for three decades.