Josephine Herivel (59) is the daughter of mathematician John Herivel who was a key figure in the team who cracked the German Enigma ciphers in 1940.
ITV News published footage of her, taken during a documentary which was shot in 1997, about the death of a woman who was also a member of the far-left commune in which they lived.
Her identity was revealed as the first picture also emerged of Aravindan Balakrishnan, the man accused of keeping Ms Herivel and two other women captive for 30 years.
He was caught on camera attending the inquest into the death of commune member Sian Davies (44) in 1997. She died after falling from a bathroom window at a home the group were sharing.
Fresh information about the three women and their cult-like existence emerged after the connection with Ms Davies became apparent.
It is thought that the youngest of the three 'slaves', a 30-year-old known as Rose who may have been born into the sect, is in fact Ms Davies' daughter.
Three women claim they were held as slaves by Mr Balakrishnan (73) and his wife Chanda (67) for 30 years. They were freed last month after Ms Herivel made a phone call to the Freedom Charity, using a helpline number she had seen on TV.
As a child, Ms Herivel was brought up with her two sisters, Mary and Susan in Belfast. She joined Mr Balakrishnan's extremist collective in the 1970s after moving to London to study.
She was educated at the prestigious Belfast Methodist College, and was a talented musician before moving to London, where she became involved in the far left.
Her father John Herivel was recruited to Bletchley Park from Cambridge University in 1940, and after being trained by Alan Turing worked in the now legendary Hut 6.
He was responsible for coming up with an ingenious method to crack codes which became known as the Herivel Tip or herivelismus.
After the war he worked as a teacher, but eventually returned to Belfast with wife Elizabeth, who also worked at Bletchley Park. When he died in 2011, obituaries only made mention of his two other daughters, who now live in London.
A friend of the family said they had tried to make contact with Ms Herivel for years, but without success.
As one of the core figures in Mr Balakrishnan's tight-knit circle of loyalists, Ms Herivel was prosecuted in 1978 after police raided the group's south London bookshop and headquarters.
Appearing in court alongside five fellow cult members, she displayed the extent to which she had fallen under the spell of the cult, by refusing to recognise the court and denouncing the judge as a "Fascist lackey".
Ms Davies died in hospital, seven months after falling from a bathroom window at a house in south London where Mr Balakrishnan, his wife and supporters were living.
At the subsequent inquest, the coroner criticised the other women living there after learning that they had failed to inform Ms Davies' family of the accident, telling them instead she was on holiday in India.
When journalists later approached Ms Herivel at the house to inquire what had happened, she accused them of being parts of the "Fascist state".
She refused to discuss Ms Davies' death or the arrangements inside the sect.
The Malaysian woman among the trio was identified earlier this week as Aishah Mautum.
The ITV footage also shows a woman who it identified as Aishah waving away the press from their home following the inquest into the death of Ms Davies.
The three women were freed from the flat in Brixton south London where they had been living for the past five years, and taken into the care of the police and specially trained charity workers.