Ofsted rejects claims of inspection tip-offs
An Ofsted investigation says it found no evidence that three academy schools in Norfolk had been improperly warned about when to expect inspections.
But the watchdog says the chief executive of the academy trust had mistakenly been copied into an email with an inspection schedule.
Ofsted says the date of the inspection was then changed.
A statement from the Inspiration Trust says the findings confirm the "highest levels of integrity" at its schools.
The inquiry followed reports in the Observer newspaper that three academies had known in advance about impending Ofsted inspections, giving them an unfair advantage.
There was a subsequent report that a parent had warned Ofsted of this more than a year ago.
The schools, Ormiston Victory, Thetford Academy and Great Yarmouth Primary Academy, had been overseen by Dame Rachel de Souza, currently the chief executive of Inspiration Trust which runs two of the schools.
Ofsted's director of quality and training, Sir Robin Bosher, carried out the investigation and says he found no evidence to substantiate the claims.
But he found that an inspection schedule had been "emailed in error" to Dame Rachel, in her role as a part-time inspector.
She was the chair of governors of Great Yarmouth Primary Academy, "a school named on the schedule with the planned date of its next inspection".
Dame Rachel is currently chief executive of the trust which runs the school, the Inspiration Trust.
The trust's chairman is Theodore Agnew, a non-executive director of the Department for Education and chairman of the Academies Board, responsible for the oversight of the academies programme in England.
Ofsted's report says that Dame Rachel told them she had not passed on any of the information from the email - and the investigating team found nothing that would "cast doubt on this assertion".
To maintain public confidence in the integrity of the inspection process, Ofsted says it carried out an unannounced inspection of Great Yarmouth Primary Academy this week.
The investigation examined why there might have been a "perception among a number of people associated or familiar with the schools" that school leaders had prior warning of inspections.
The three schools were kept in a longstanding state of "Ofsted readiness", the investigating team found, even though they did not have any certainty of when inspections would actually take place.
It was also possible that staff could accurately predict the likely timing of an inspection - and this could have been misinterpreted as insider knowledge.
The Ofsted interviewers found the belief that the schools had advance warning was "more prevalent" among head teachers in other Norfolk schools, than among staff or parents in those being investigated.
Inspectors rejected claims that there was any improper use of temporary staff during Ofsted visits.
Following the investigation, Sir Robin recommended that Ofsted should examine "processes around confidentiality and preventing conflicts of interest".
He also suggested a more flexible approach to make the timing of Ofsted inspections less predictable.
A spokesman for The Inspiration Trust said: "Sir Robin Bosher's report utterly refutes allegations of irregularities about Ofsted inspections of two of our schools, and a third school where our chief executive was executive principal at the time.
"We maintain the highest levels of integrity and transparency at our schools. This report underlines that."