This week the National Association of Head Teachers (NAHT) will announce the findings of its Accountabilty Commission into what it describes as a high-stakes low-trust culture facing English schools.

Tes can reveal that the commission concludes that a system of Ofsted inspections and government tables and targets is doing more harm than good.

Throughout this week Tes will be running a series of reports on the commission’s findings and recommendations.

Here are five key findings that the expert panel has made about Ofsted.

1. Ofsted cannot deliver reliable judgements about schools.

The most damning finding in the report is that the current inspection model does not allow Ofsted to make reliable judgements about schools.

The commission concludes that the inspectorate’s reports are giving parents a false assurance about the effectiveness of the schools they inspect.

The report questions what inspectors can establish in one or two days.

It states: “Even a full inspection only lasts two days and this means inspectors have to make significant, complex judgements about a school in a very short space of time with limited evidence to draw on.”

2. Inspections create needless extra work.

School leaders warn that the importance of securing a good inspection outcome and the fear of not being “Ofsted-ready” drives considerable activity in too many schools that could be better spent focused on improving teaching and learning.

The commission highlights how tracking pupil progress and predicting outcomes have become an integral part of some schools to ensure they are prepared for Ofsted.

It says the ability to show near real-time information on the progress of every pupil in a school, alongside predictions of future performance, has been interpreted as evidence of “leadership grip” by some inspectors.

However the commission says that much of this analysis has been proven to have no validity or usefulness to teaching and learning.

It concludes that, the need to be “Ofsted-ready” and have evidence prepared creates significant workload burdens.

3. Headteachers can feel a sense of panic and vulnerability

The commission warns that headteachers’ reaction to dropping a grade can be one of panic and vulnerability.

And it warns that the pressure of accountability is felt by leaders of schools, regardless of grade.  

It also warns that headteachers too often feel they are held to account through an Ofsted inspection before they have the opportunity to make an impact at the school they are leading.

4. Compliance to Ofsted creates a tick box culture

The commission says that a “tick-box” culture has taken hold in many schools, where compliance with what Ofsted is perceived to want has become the overwhelming driver of improvement activity.

It says: “The secrets behind great schools cannot be found in the Ofsted inspection framework and if we simply continue to benchmark ourselves against it we will never unleash the full potential of schools. Internationally, we will be anchored to average, as others rise further and faster.”

5.  Ofsted is at a crossroads and a decision needs to be made about its future role

With questions about Ofsted’s reliability and the number and length of the inspections it carries out mounting, the commission warns that the inspectorate is at a crossroads.

It says that at present Ofsted provides much less assurance of effectiveness and provides less opportunity for inspectors to get underneath the skin of a school.

The commission report says: “The choice is stark - either the government chooses to invest heavily to ensure reliable inspection for all, or we revise our expectations about what to reasonably expect from the inspection process.”

And it adds that it is highly unlikely that Ofsted is going to get any more money anytime soon.

An Ofsted spokesperson said: “We welcome any constructive addition to the important debate about our school accountability system.

“That is why our chief inspector, Amanda Spielman, was very happy to take part in the NAHT Commission and will participate in their launch event later this week.

“We recognise that inspection practice cannot stand still, and we believe that Ofsted’s role should complement, rather than magnify, other elements of the accountability system.

“We are currently developing our new education inspection framework and aim to consult on the details in the new year. We look forward to the NAHT’s contribution to that work.”