A couple suspected of keeping three women as slaves have been bailed until April.
The couple, said to be Maoist activists Aravindan Balakrishnan and his wife, Chanda Pattni, were arrested in November after one of their alleged victims contacted a charity.
Scotland Yard did not name the pair, but said: "A 73-year-old man and a 67-year-old woman arrested on November 21 2013 in connection with an investigation into slavery and domestic servitude have been further bailed until a date in April pending further inquiries."
It is claimed three women - a 30-year-old Briton, a 57-year-old Irishwoman and a 69-year-old Malaysian - were effectively brainwashed into remaining in a political collective for more than three decades.
The arrests came after one of the women contacted the Freedom Charity following television coverage on forced marriages.
Staff from the organisation, which advises and supports victims of forced marriages or honour-based violence, then contacted Scotland Yard, who agreed to wait a number of days before making arrests.
Footage later emerged of two of the women in a 1997 documentary about Sian Davies, who was fatally injured when she fell from a window of a house used by the political group in Herne Hill, south London.
One of them, thought to be Josephine Herivel, now 57, was seen telling the film makers: "You're part of the fascist state."
Police were not called to the house at the time Miss Davies was hurt, but detectives are now looking again at coroner's files to see how officers were involved in the inquiry.