Fraud at a Sawtry school run by “sex dungeon” head James Stewart is believed to have taken place while it was still under the control of Cambridgeshire County Council, a report has said.

Financial governance of the then Sawtry Community College was described as "very weak" and that opportunities to address problems as far back as 2000 had been missed.

The report to the county council's Children and Young People's Committee on May 22 was drawn up after former principal Stewart was jailed for four years last October after admitting four offences of fraud and a charge of misconduct in public office.

Stewart obtained more than £100,000 of school funds and lavished money on his office which he converted into a "sex dungeon" where he had an affair with another adult.

Former deputy principal Alan Stevens admitted two frauds and was given a suspended prison sentence.

The report said there had been problems with "whistleblowing" at the school and that some members of staff did make efforts to report concerns, despite fears about losing their jobs and others stood up to intimidation and bullying.

The report said: "The fraud and misconduct which occurred at Sawtry took place over a significant period of time. Although the prosecution of the former principal and vice-principal related to charges between 2011 and 2014 as these were the years covered by the forensic audit of the school's accounts, there is evidence to suggest that fraud and misconduct were taking place at the school for a number of years prior to this period, including when the school was still maintained by the local authority."

It said the majority of the fraudulent expenditure was made through the School Fund - non-public funds to held by the school to pay for its activities.

The school went into special measures before joining the Cambridge Meridian Academies and is now known as Sawtry Village Academy. Its latest Ofsted rated it "good" with an "outstanding" sixth form.

Mark Woods, chief executive of Cambridge Meridian Academies Trust, said: "We are pleased the opportunity to fully investigate and learn the lessons of the past has been taken by the local authority. It is clear that this culture of leadership persisted unchecked for a number of years, long before the school became an academy.

"The new principal, Sarah Wilson, worked closely with the Education Funding Agency and Cambridgeshire police to forensically investigate the wrongdoing of Mr Stewart. However, this only focused on a brief period since the school became an academy in 2011 and evidence was clearly documented. We are pleased that the council agrees that there is evidence to suggest that this wrongdoing had been taking place over many years before this.

"While this wrongdoing and culture of leadership has undoubtedly damaged the education of a community for many years, it is pleasing to see the academy complete a dramatic transformation since his resignation."

A Cambridgeshire County Council spokesman said: "Councillors are considering a series of recommendations to ensure that lessons are learnt and that processes are in place to prevent incidents of this nature from happening again.

"The Council's Children and Young People Committee will be examining awareness of, and approach to, financial governance and whistleblowing at the school, school culture and staff experience, financial governance as well as the wider process and associated action plan for tackling and dealing with schools causing concern, whether these are local authority maintained schools, academies or free schools.

"These recommendations result from an Internal Audit report commissioned by the Executive Director of People and Communities to ensure that all lessons were learned from the issues that arose. This involved Internal Audit visiting Sawtry Village Academy in March, in order to review relevant documentation from the school and speak to staff and a governor who were at the school during the period of the offences taking place and reviewing other relevant evidence and speaking to staff at the Local Authority."

The spokesman said: "We acknowledge that advice was given to the school in 2011 that was not in line with our whistleblowing processes. As part of the lessons learned, steps are being taken to ensure that staff are aware and always follow robust whistleblowing procedures. Our whistleblowing policy and poster was recently updated with a wider range of contacts that staff can raise concerns with, including contacts outside the authority, and a letter was sent to all maintained schools on 17 January requiring schools to display the poster."