More than 10 years ago, a school not too far from where I was teaching was awarded an “outstanding” grade by a visiting inspection team. Other schools in the locality tried to contain their surprise at the outcome. It’s not to say that everyone thought the school dreadful - just that there were questions about how an accurate a judgement it was.

Those who received pupils from the school in previous years hadn’t been entirely confident in the accuracy of the assessment processes at the school - and that was long before the trials of life without levels.

It would be unfair of me to name that school or to continue to cast aspersions on it. More than a decade later, it is surely a very different place. The head at the time has long-since gone, as - no doubt - have many of his colleagues. Even an excellent school can expect to lose staff over time. It wouldn’t be fair to label the school based on my out-of-date evidence.

Except, of course, that’s almost exactly what happens. For more than a decade, that school - along with others - has been able to ply its trade on the premise of it being an “outstanding” establishment. No matter that the judgement might have been suspect. No consideration for the possibility that the whole staff might have completely changed in the intervening period. In some cases, no thought given to the fact that the character of the school might have changed significantly in the years since it was last visited: the infant school that’s now a through primary, the one-form entry school that has now doubled in size, the catchment that has now changed into an area of deprivation.

Risk-assessed approach

It doesn’t take much to realise what a crazy system this is. Of course, the school I mention hasn’t escaped inspection altogether. The kitchen staff will have been under far more regular scrutiny than the headteacher - or headteachers - over the years.

Like Ofsted, local authority food safety teams run a risk-assessed approach. Also like Ofsted, higher levels of risk are likely to lead to more frequent inspections. But there the similarity ends.

The Food Standards Agency sets out a framework where high-risk businesses are inspected every six months. Lower-risk establishments might wait up to two years. Scoring full marks on the inspection carried out this year won’t be a lifetime of freedom from health and hygiene inspections. That would be foolish. The chef could move on, the whole highly-trained kitchen team could end up being replaced by cheap, poorly-trained new staff, the menu offer might change completely.

Robust evaluation means keeping an eye on the places that have a good history. They don’t wait for an outbreak of disease before going back to check things are in order.

Not so with education, it seems. So long as you don’t oversee a catastrophic decline in results, you’ll probably be OK. Even with safeguarding - that central thread of most current inspections - you can escape scrutiny for more than a decade, so long as your Sats results aren’t too bad.

Whatever you might think about Ofsted gradings, the current exemption from inspection for some schools is absolute madness. No amount of remote desktop scrutiny can tell you that safeguarding processes are secure, any more than they can check that meat is being stored in accordance with hygiene regulations.

The difference appears to be that government is happy to wait for a safeguarding disaster, more than a hygiene one.

Michael Tidd is headteacher at Medmerry Primary School in West Sussex. He tweets as @MichaelT1979