Josephine Herivel, in her fifties, is the daughter of John Herivel, one of the leading codebreakers at Bletchley Park who deciphered the Enigma code.
Reports suggest that last week's arrests of slavery suspect Aravindan Balakrishnan and his wife Chanda in Brixton, south London, were triggered when Ms Herivel raised the alarm.
The couple were arrested on suspicion of slavery related offences amid claims that three women were held against their will for more than 30 years.
Brought up with her two sisters, Mary and Susan in Belfast, she joined Balakrishnan's extremist collective in the 1970s after moving to London to study, turning her back on her family.
When her father died in 2011 obituaries only made mention of his two other daughters, who now live in London.
Attempts by her family to make contact failed, according to family friend Frances Presley.
She said: "They have tried to contact her for years. I know she was involved in some kind of cult group. My understanding is that she cut herself off (from the family). I know they have always tried their best."
Miss Herivel was prosecuted in 1978 after police raided the group's south London bookshop and headquarters. She and five fellow cult members appeared in court charged with obstructing police officers.
She refused to recognise the court and denouncing the judge as a "Fascist lackey".
Miss Herivel was also with the sect when one of its members, Sian Davies died in mysterious circumstances in 1997.
Miss Davies died in hospital, seven months after falling from a bathroom window at a house in south London where the collective were living.
Documentary footage of Balakrishnan and his wife have also been uncovered by ITV News.
The pictures were shot in 1997 as part of a documentary about the death of Ms Davies.
It is thought Miss Herivel lived with the group for more than 30 years before contacting the Freedom Charity and reporting that she and two other women were being held against their will.