Early Ofsted inspections aimed to replicate visits from Her Majesty’s Inspectorate. Most schools never had one of these, but when they did happen you knew about it. One HM inspector for each subject, in school for four days, and the lead HMI expected to work all night on the Thursday to deliver the report next morning. The handbook based on these inspections was huge. As Ted Wragg said at the time, it “frightened people to death”.

Over time, the handbook was slimmed down, and a system of short inspections developed for the most successful schools. This used the same preparation as a full inspection, but saved time and money by focusing on points arising from pre-inspection evidence. Short inspection reports were cost-effective, concise, and valued by schools and HMI. Inspection had, to a degree, been made proportionate. But only to a degree. Most schools chosen for short inspections had stable staffs, and strong parental support. Schools in difficult areas were under-represented.

At Ofsted’s 10th anniversary conference in 2003, Charles Clarke, Secretary of State, wondered “whether this light-touch regime is light-touch enough”.

Soon afterwards, short inspections were abolished, and schools that would have had a short inspection had a full one. This seems inexplicable, but Mr Clarke also said that, for a super-short inspection to be valid, a school had first to have a full one. After 2003, hundreds of schools received full inspections unnecessarily.

Mr Clarke’s extra light-touch model has proved popular with most schools because it reduces stress on teachers - the main, and serious, weakness in previous inspections. It has, on the other hand, cut so deeply into the time inspectors spend in schools that it is no longer possible to claim that inspection reports are based on first-hand evidence. Does this matter?

Warwick Mansell’s report on contextual value added scores (TES, May 12) shows that it does. Analysis of Minsthorpe community college’s data by the Fischer Family Trust suggests the Yorkshire school is doing better than its Ofsted CVA score indicates. An inspection should be able to settle the issue by means of direct evidence of teaching, learning and achievement, showing where the school is doing well, and providing reasons, based on evidence, for any criticisms.

But these inspectors saw only 22 lessons in a school of 1,800 students, where it is likely that 350-400 lessons will be taking place daily. Half of the lessons were in the maths department, and some must have been in the sixth form.

The school is entitled to think that inspection judgements were based on second-hand evidence, simply because this is all the inspectors have available. And test results are not always reliable. Sats papers change each year, and the passmarks for each level can be moved up and down as examiners wish. They do not always reflect national curriculum levels - for example, a pupil can receive level 4 in English without using joined handwriting, even though the curriculum nominally requires this from level 3. So a school that teaches handwriting may get lower Sats scores than it deserves, while one that does not may get higher ones.

An inspection based on first-hand evidence would spend time analysing samples of children’s work in detail, comparing progress against the national curriculum. A day in a small primary school does not allow this.

The school is, in effect, judged on its Sats alone, and the inspector might just as well have stayed at home.

So, too little time to see teaching - and no more recognition of excellence through cameos in the report. No time to analyse children’s work properly.

And what of Ofsted’s claim that it is putting emphasis on pupils’ and teachers’ views? It is downright fraudulent. There is much less time to talk to pupils, and none to investigate difficult issues such as bullying.

Pre-inspection meetings for parents under the previous system were rarely well attended, but at least allowed parents to see the inspector and get a fair hearing. The lead inspector had time to read their comments, analyse questionnaires, and brief the team to investigate. They now barely have time to open questionnaires, let alone act on parents’ responses.

Ofsted presented superlight inspections as a laser, and patronisingly told anyone who questioned them that they didn’t understand them. A senior HMI, now retired, describes them more accurately as a candle. They are more like a pre-inspection visit than an inspection, and do not generate enough first-hand evidence to make sound judgements or recommendations. The system is, therefore, invalid. Short inspections should be restored for all schools, backed by a full inspection before a school is placed in a category causing concern.

Letters 26

John Bald is an independent consultant and was a registered Ofsted inspector from 1997 to 2005