Authorities in Rotherham were warned about child sexual exploitation in 2003 - and given a list of the suspected main offenders - and told three years later that the problem was established and very serious, two new reports have revealed.
Dr Angie Heal provided a list of potential abusers as part of a report on the links between grooming and drug dealing in 2003, but police and council officials failed to act. That report and another from 2006 have been released under the Freedom of Information Act to The Sheffield Star.
Dr Heal, who has since left the police, said she has ‘no idea’ whether any of the suspects she tipped her bosses off about were ever convicted.
Last year an inquiry found 1,400 children were abused by gangs of men, mainly of Pakistani origin, in South Yorkshire between 1997 and 2013.
The inquiry concluded: "It is hard to describe the appalling nature of the abuse that child victims suffered."
Last years report found that in more than a third of the 1,400 cases the youngsters were already known to child care agencies. Girls as young as 11 had been raped by large numbers of men.
The inquiry said there had been "blatant" collective failures by the council's leadership.
Professor Alexis Jay, who wrote the report, said she found examples of "children who had been doused in petrol and threatened with being set alight, threatened with guns, made to witness brutally-violent rapes and threatened they would be next if they told anyone".
Prof Jay said: "They were raped by multiple perpetrators, trafficked to other towns and cities in the north of England, abducted, beaten and intimidated."
Two new reports provide further damning evidence of the police and council's failures.
In the first report Dr Heal warned in 2003 that there was no room for complacency over the allegations. However, three years later she had to prompt police to act again, telling authorities the problem was established and serious.
Both reports went to senior police officers and council officials but nothing was done.
Dr Heal told the BBC: "I just cannot fathom it at all as to why no action, no concerted action was taken."
She added: "It meant that a significant number, over 1,400, continued to be abused, assaulted, raped, their families devastated by what happened."
Dr Heal said that the authorities failure to act "makes me really angry and upset".
The Star reports that police not only failed to act, but when they were finally spurred into action, were so slow key opportunities to crack the case were missed.
Citing the released reports, it said one man had told police that a significant number of teenage girls had been visiting his neighbour's house, and that he had offered his residence as an observation post. Police took seven months to get back to him, by which time the suspected abuser had moved. In another case a teenager told police she had been raped by a "well-known heroin dealer", only to be charged with theft herself. A rape investigation was never launched.
South Yorkshire Police and Crime Commissioner Alan Billings told the BBC that agencies knew about Dr Heal's reports at the time but were focusing on other issues.
He said her reports were "utterly shocking", saying when you read them there's "no hold's barred".
Billings laid the blame beyond police and council officials, saying Dr Heal's reports also went to safeguarding boards and the national government, "it was widely known what she said".
He said: "I think there are more people that have questions to answer than the police. The only sense I can make of it is that at that time, police were prioritising other things like burglary and car theft. I don't think anyone understood what grooming was."
In a statement, South Yorkshire Police admitted to past failings and pointed to an ongoing investigation by the Independent Police Complaints Commission into misconduct issues.
It said it had made "significant progress" in tackling child sexual exploitation but understood more "needs to be done".