The Irishwoman allegedly held captive in a South London house is believed to have been identified.
ITV news claims that the woman, named as Josephine Herivel, appears in a 1997 documentary on the death of Maoist Sian Davies.
Her identity became apparent after the first picture emerged of Aravindan Balakrishnan, the man accused of holding Ms Herival and two other women captive for 30 years.
A camera captured him attending the inquest into the death of Ms Davies, who died after falling from the bathroom window of a house rented by Mr Balakrishnan and his wife Chanda.
New information was revealed about the far-left commune where the three women lived after the video footage indicated the link between them and Ms Davies.
It is believed that the 30-year-old woman, known as Rose, may have been born into captivity and could be Ms Davies’ daughter.
Further claims suggest that the Irishwoman in the video was responsible for calling the Freedom Charity to alert them of the three women’s plight last month.
Ms Herival originates from Co Armagh and was the daughter of John Herivel, a World War II code-breaker, whose clever method to crack codes became known as the Herivel Tip.
During her childhood she was brought up with her two sisters, Mary and Susan, in Belfast, where she attended Belfast Methodist College.
She moved to London in the 1970s to study, and it is during this time that Ms Herivel is believed to have joined Mr Balakrishnan’s extremist Maoist group.
He and his wife were arrested last week on suspicion of the slavery of three women for more than 30 years.
The alleged victims – a 57-year-old Irishwoman, 69-year-old Malaysian and a 30-year-old Briton – are said to be “severely traumatised” according to the Metropolitan Police’s Human Trafficking Unit.
Police have confirmed that there are ongoing inquiries relating to a total of 13 London addresses that are linked to the couple.