We urgently need a new focus for Ofsted and the way schools are inspected.

It is more than 20 years since the dawn of the Ofsted age, which changed inspection in England beyond all recognition. During that time, endless changes have been made to its organisation and remit, as well as its methods and approaches. Now, fierce debate is raging about the need for more change, particularly when it comes to Ofsted’s responsibility to schools.

Part of this discussion arises from a growing disquiet about Ofsted’s reliability and independence. Doubts have been raised about the unreasonable variability in inspectors’ judgements of individual schools. The way in which the organisation itself may be unduly influenced by government is also under scrutiny.

I believe the time has come to give greater respect and trust to schools by shifting the balance of inspection to a rigorous self-evaluation. Of course, this would still have to be externally scrutinised and validated. This is not to deny a role for school inspection - indeed, it would demand a more appropriate, stronger role for Ofsted.

So what would this new Ofsted and school inspection regime look like? It should focus on three main tasks.

Redefining inspection

First, a rethought Ofsted should concentrate on assuring the quality of school inspection. The reliability of individual inspections and the many changes in the inspection framework have been hotly debated of late. This issue of variability has now persuaded Her Majesty’s chief inspector Sir Michael Wilshaw to accept that “outsourcing” inspections to private contractors should be replaced by the “in-house” model.

A bigger question must be resolved before we look at this practical solution, however: is the present model of school inspection fit for purpose? Increasingly, publicly available information about attendance and pupil performance at key stages 2, 4 and 5 determines perceptions of a school and acts as the starting point for school inspection outcomes. It is rare for a verdict to fly in the face of the data profile. If it happens, it will be because the school’s self-evaluation is so persuasive that the inspector is satisfied it outweighs the data.

This suggests that a better form of school inspection could be introduced, with a framework determined by Ofsted but operated at school level by regional bodies responsible for both the inspection system and school improvement.

The region would supervise a timetabled programme of school self-evaluations, which would be externally moderated. It would be for Ofsted to prescribe the detailed requirements of that process. Teachers from other schools should be included to encourage staff development and the spread of interesting practice. Schools’ ratings would be based on both that process and the usual data, expanded to include pupil participation in extracurricular activities and surveys of pupil commitment and parental satisfaction. Outcomes would be publicly available.

Ofsted would inspect the regions - and in the process inspect some schools at random. Such a system would be more rigorous and reliable. It would also be less expensive. It is worth reminding ourselves that we are the only developed country with such an elaborate system of school accountability, based essentially on professional mistrust. This proposed new system corrects that fault without any loss of quality.

Redefining evidence

The second key aspect of a revitalised Ofsted concerns evidence. The inspectorate must provide reliable evidence of the quality of schooling and standards in schools. The organisation is at its best when it conducts periodic surveys of the quality of teaching and learning in various core and foundation school subjects and in the five phases. These investigations provide invaluable insights into issues affecting schools and school improvement, such as transition, truancy, behaviour and provision for particular groups of children such as those with special educational needs.

Ofsted achieves this by recruiting, meticulously training and deploying inspectors with proven track records of success. This work remains important and would become even more so in the light of the third role set out below.

The chief inspector’s annual report on the state of our schools would be an important part of this second task (and would contribute to the third). In effect, Ofsted’s role would be the educational equivalent of the Office of Budget Responsibility.

Redefining advice

The third role for a reformed inspectorate would be to provide independent advice to the education secretary when he or she is considering changes in policy and priorities. Increasingly, the schools sector has suffered from secretaries of state making policy on their own, sometimes driven by idiosyncratic, personal views rather than evidence. Ofsted has a large part to play in reducing the likelihood of this happening - and doesn’t fulfil its potential to do so at the moment.

Ofsted should be responsible for a process that incorporates its own evidence, research evidence and the recommendations of any select committee - so that no education secretary can ever be in any doubt about what the evidence says. With this three-part plan, Ofsted could move on from its controversies and play a bigger part in improving education in this country.

Sir Tim Brighouse is a British educator and a former schools commissioner for London