Hundreds of schools in England have been downgraded by Ofsted after being reinspected for the first time in years.
According to the watchdog, only 17% of 370 “outstanding” schools kept their grade when they had a full reinspection in 2021-22.
Ofsted said it had reviewed more than 500 institutions in the last school year that had previously been exempt from regular inspections, because they had been rated as “outstanding”, the highest grading available.
It meant the primary and secondary schools would not have a full inspection unless specific concerns had been raised.
The average amount of time that the reinspected schools had gone since their last full review by Ofsted officials was more than 13 years, it said.
The watchdog’s chief inspector, Amanda Spielman, said the results indicated that “removing a school from scrutiny does not make it better”.
The former education secretary Michael Gove introduced the freedom from inspections for “outstanding” schools, which was then abolished in 2020. Ofsted is now prioritising inspections in schools that have gone the longest without being reviewed.
The fall in grades comes alongside a new criterion for inspections, introduced in September 2019. It focuses on the curriculum and overall “quality of education”.
Inspections were then halted during the Covid-19 pandemic, which meant that they only properly got back under way at the start of the last school year.
Headteachers have raised concerns at the impact of the changes, which have included exam results not being taken into account.
School leaders have also said that they are being downgraded if pupils cannot answer on-the-spot questions about the dates of battles in history or names of rivers in geography.
Last year Spielman said that the number of schools graded “outstanding” would reduce, and that one in 10 would be “more realistic”, down from one in five in November 2021.
Of the schools that previously held Ofsted’s top ranking, 62% were found to be “good” last year, one grade below, and 21% were judged to “require improvement” or “inadequate”, the lowest two ratings given by Ofsted.
Ofsted’s director of education, Chris Russell, has said some newly downgraded schools may not have actually worsened, but instead that the new inspection framework has made the “outstanding” grade more “challenging and exacting”.
The regulatory body said while the schools that were reinspected might not be representative of all exempt schools, their performance was concerning.
It added that a higher proportion were graded as “requires improvement” or “inadequate” than on average across all schools. It added that this was especially the case for primary schools.
Spielman said: “Regular inspection gives parents confidence in the quality of their child’s school. Exempting outstanding schools deprived parents of up-to-date information. It also left a lot of schools without the constructive challenge that regular inspection provides.
“The exemption was a policy founded on the hope that high standards, once achieved, would never drop, and that freedom from inspection might drive them even higher. These outcomes show that removing a school from scrutiny does not make it better.”