The couple accused of holding three women as slaves for more than 30 years have been linked to 13 addresses across the capital, it was reported.
The three alleged victims - a 30-year-old Briton , a 57-year-old Irishwoman and a 69-year-old Malaysian - are believed to have suffered years of "physical and mental abuse" at the hands of the man, who is 73, and woman, aged 67.
Police carried out house-to-house inquiries over the weekend in and around Peckford Place, Brixton, south London, where the three women were found.
The number of properties associated with the couple, of Indian and Tanzanian origin who came to the UK in the 1960s, suggests the women may have been moved around London repeatedly over the last three decades, the Guardian said.
Yesterday Home Secretary Theresa May said tackling modern slavery in Britain was a "personal priority", saying many other victims were "hidden in plain sight" across the country.
"It is walking our streets, supplying shops and supermarkets, working in fields, factories or nail bars, trapped in brothels or cowering behind the curtains in an ordinary street: slavery," she wrote in the Sunday Telegraph.
"Something most of us thought consigned to history books, belonging to a different century, is a shameful and shocking presence in modern Britain."
The youngest of the three alleged victims is said to have written letters to a neighbour, telling of her life as being "like a fly trapped in a spider's web".
The woman became infatuated with neighbour Marius Feneck, 26, the Guardian said, reportedly writing him more than 500 letters in seven years.
One letter apparently tells of how she suffered "unspeakable torment" behind locked doors and windows, and of how she was terrified that her captors - "these evil criminals... who dare to call themselves 'my relatives'" - might do something to him.
On Saturday Metropolitcan police commander Steve Rodhouse said that two of the women had met the male suspect through a "shared political ideology" and lived together in what he described as "a collective".
It emerged that the couple on bail were previously arrested in the 1970s, although police have not said why they were detained.
Police have recovered a birth certificate for the 30-year-old woman, who is believed to have lived her entire life in servitude, but no other official documents for her have been found.
The case came to light after the Irish woman rang the Freedom Charity last month to say she had been held against her will.
The Met said that part of the agreement on October 25 when the women were removed from the address was that police would not take any action at that stage.
None of the women was reported missing after being rescued, police said. All three are now in the care of a specialist non-governmental organisation.
Some 37 officers from the Met's human trafficking unit are working on the case.