Ofsted has changed several schools’ inspection reports after publication because they contradicted its own official guidance, the watchdog has admitted.

Before Christmas, Ofsted issued new advice insisting that its inspectors did not favour a particular teaching style. Inspection teams, it said, would not criticise teachers for talking too much or mark them down for failing to use a range of different activities in their lessons.

However, it has emerged that six school inspection reports published this month were retrospectively amended after their release, because they did not comply with Ofsted’s guidance.

The publication of the reports of all other inspections carried out before Christmas has also been put on hold to allow further checks for other errors, Ofsted told TES.

The discrepancies related to reports of inspections carried out in December - before the new Ofsted guidance was issued - but only published several weeks after it had come into effect.

The most high profile school affected was Durand Academy, best known for the controversy over its plans to bus hundreds of teenagers from London to a boarding school in the South Downs.

Despite being lauded by education secretary Michael Gove as an “outstanding school doing a wonderful job”, Durand’s most recent inspection saw it unexpectedly downgraded from outstanding to good after a visit from inspectors in early December.

Earlier this month, the report was briefly published on the Ofsted website - but swiftly removed. 

A revised version has now been posted online. Janet Downs, a contributor to the New Schools Network website has pointed out that several criticisms of teaching practice at the school have been replaced or removed from the new version.

A Durand spokeswoman told TES that it was “surprising” that, despite attainment being “well above” national averages and Ofsted’s recognition of pupils’ “particularly strong” attitudes to learning, “the style [of teaching] adopted by the school” was “essentially cited” as a reason that outstanding status was not achieved.

“It is absolutely right that new guidance has come in to prevent judgments being made on this basis going forward and it is only a shame that this was introduced and retrofitted after Durand’s inspection took place,” she added.

Education blogger Andrew Old has also pointed out several amendments to the report for John Ruskin School in Coniston, Cumbria, which has been placed in the “requires improvement” category.

An Ofsted spokesman told TES that it had made several minor changes to six reports, but no overall grades were affected. It had delayed publishing the reports of all other schools inspected before Christmas for “final quality assurance checks to confirm [inspectors] were following the latest published guidance, especially around teaching.

“This exercise is now complete and the reports are expected to appear on the website from early tomorrow onwards,” he added.

Reporting by Stephen Exley.