Criticism is one thing, says former headteacher Hilary Carnihan, but unjust criticism is quite another. She believes inspectors judged her school unfairly - and has statistics to prove it.

Tables from the Qualifications and Curriculum Authority show that south London’s Lewisham Bridge primary school was scoring in the top 25 per cent of similar schools for key stage 2 English, and in the top 50 per cent for maths.

Sadly for Ms Carnihan, a rival quango, the Office for Standards in Education took a contrary view. Last November it published a report putting the school under “special measures”. The main evidence? The fact that standards of teaching and learning were too low.

It seems the former head’s experience is not uncommon. A TES survey last week suggested OFSTED’s judgment is questionable in at least one in six cases of failing primary schools - where the results in English and maths show they are making better-than-average progress.

According to the QCA’s curriculum analysts, Lewisham Bridge is doing very well for a school where nearly half the pupils take free school meals, many are transient from year to year, and many more have special educational needs.

Despite this, OFSTED’s report marked the end of Ms Carnihan’s 12-year headship at Lewisham Bridge. This is the pattern for a significant number of heads where the school is described as failing.

Ms Carnihan had no intention of leaving. But last November’s report was followed by a four-month parental campaign to remove her. By April she’d had enough, and resigned.

“The main criticism in the OFSTED report was that the teaching and learning score wasn’t high enough,” she said this week. “They did pick up some management failings and said we were poor value for money. But it was essentially the fact that, in their subjective opinion, the teaching and learning throughout the school didn’t reach a 75 per cent mark.

“In fact the first thing anybody who came into our school said was: ‘Well your results are good’. They also said how delightful the children were. Lewisham’s advisory service was shocked by the report. We’d had an audit the year before and they’d not found any concerns.

“When the QCA’s benchmarks came out, I sent a letter to the parents saying that in English we were in the top 25 per cent of the country.”

This had little effect. “Unfortunately part of the campaign against me just went beserk. A group of parents was determined to get me out. And when the snowball starts to roll no one can stop it. People turn against you for no apparent reason.

“In the end, there were so many nasty letters coming to me I didn’t think the school was safe. So for the sake of the school I resigned.

“It’s not so much that I feel bitter personally, but it’s a massive injustice that’s going on in our society. As a school we did a lot more than was ever said and we were achieving more than we were ever given credit for. The children were working so hard and did not deserve to be told they were failing.

“As far as I know the acting head has the full backing of the teachers and authorities. It should be able to come out of special measures very quickly.”

Analysis, page 21