Cambridgeshire County Council failed to protect a 15-year-old girl from being sexually abused by her teacher, the Victoria Derbyshire show has learned.
The girl, "Abigail", was abused multiple times a week in the 1990s - in the classroom and at the man's home.
A social worker had previously written to warn the council about the teacher - who cannot be named - but he was allowed to continue teaching.
The council offered its sympathy to the victim.
It has agreed an out-of-court settlement of up to £550,000 with Abigail.
'I'll never forgive him'
Abigail - not her real name - was raped and sexually abused at Sir Harry Smith Community College in Whittlesey, Peterborough, in the 1990s.
"The abuse happened four, five times a week - and it would be in the classroom store cupboard," she said, after other teachers had gone home.
"On several occasions he tied me to a radiator with a dog collar and told me not to move, and made me sit there naked."
The abuse in the classroom took place for "the first three years", from the age of 15. During this time, her abuser also started taking her to his home.
"To do that he would get me to jump in the back of the car, sit behind the seats and be covered up by a blanket - so that when he got to his house, nobody would see me go in."
She said she will "never" be able to forgive him.
"He was an adult, he knew what he was doing was wrong.
"I wanted to have children, which I've not been able to do because I've not been able to have a sexual relationship with my husband - I find it too difficult."
When Abigail reported the abuse to Cambridgeshire police in 1998, the teacher told detectives their relationship was only sexual after she was 18, and that it ended because he was in love with another pupil at the school.
After being questioned, the teacher was released without charge.
The teacher cannot be named for legal reasons, but documents seen by the BBC show the man stood trial in the early 1980s after being accused of sexually abusing two vulnerable girls at another school in Cambridgeshire, but was found not guilty.
A social worker involved with the case was so concerned about the teacher that she wrote a report to Cambridgeshire County Council.
In it she said: "I am aware of what I believe to be substantial evidence of professional misconduct - which was inadmissible in the criminal trials - that the local authority should be aware of before making the decision as to whether or not he should continue to be employed as a teacher."
The BBC believes the council - the teacher's employer - failed to pass on information to the headteacher at Sir Harry Smith Community College, despite this written warning.
The teacher later abused Abigail, and went on to become a deputy headteacher at a school in London.
He has now been banned from teaching for life.
The Department for Education told the BBC: "all public bodies and organisations working with children should have a clear child protection policy which spells out how to raise concerns with local authority children's social care services, the NSPCC, and the police".
A spokesman for Cambridgeshire County Council said: "It is deeply regrettable that these incidents happened in the 1990s, and we offer our sympathy to the victim.
"However, the school itself and the whole vetting and checking process is very different from the systems in place 25 years ago."
Tom Perry from campaign group Mandate Now - which is calling for tighter rules around child protection - told the BBC that police and schools also have a responsibility to report teachers who have committed - or are alleged to have committed - a sexual offence, to the Disclosure and Barring Service [formerly the Criminal Records Bureau].
Watch the Victoria Derbyshire programme on weekdays between 09:00 and 11:00 on BBC Two and the BBC News channel.