Lisa Holland: Inspectors claim they have evidence that most head teachers find reports fair and helpful

A survey commissioned by the National Union of Teachers has found that headteachers firmly reject the proposition that inspections are "supportive and motivate staff".

Instead the experience of headteachers is of stressed staff and disruption, with one respondent describing the inspectors' visit as "the most intimidating experience of my life. The whole effect on upon staff and pupils was negative."

Staff can be demoralised by the inspection teams, says the NUT survey

The survey, based on replies to a questionnaire by 1,250 heads and deputies, found 79% disagreeing or strongly disagreeing with the suggestion that inspections helped to motivate staff.

But there was better news for the Office for Standards in Education inspectors in other aspects of the survey, with opinion evenly divided over whether the inspectors' judgements were fair and accurate.

Even though individual testimonies from the NUT's respondents describe inspectors as "aggressive" and "abrasive", the survey shows that almost half of the headteachers believed that the inspectors "established a professional dialogue with teachers".

More damning for the inspection process was a large majority saying that they did not believe that an Ofsted inspection had led to their schools improving.

The anonymous comments from headteachers that accompany the union survey present a bleak picture of schools shell-shocked by the inspection process.

The NUT's survey of heads and deputies claims that pupils do not benefit from the inspection process

For example, a respondent said: "The headteacher at our school (I am now acting headteacher) has been off school for the past 14 months with post-inspection stress which resulted in a complete nervous breakdown."

In another report, a headteacher said that "the Ofsted inspection resulted in an overload of work, demoralised and stressed staff and had a detrimental effect on children's learning ... as a manager I found it difficult to remotivate staff and believe the Ofsted experience has a negative effect on teaching and learning".

The NUT's General Secretary, Doug McAvoy, said that the survey showed that the stress and extra work created by inspections could not be justified.