The National Audit Office (NAO) report on Ofsted, published today, is a seminal moment. The first, independent, evaluation of Ofsted since it was founded in 1992.

As a trenchant critic of Ofsted, I was initially disappointed with the NAO’s findings, which do not immediately call for its abolition (well, one could always hope).

But on a second reading of the NAO report, I came to a different view, which is that the NAO has produced a quietly devastating critique of the inspection agency.

The most startling judgement by the NAO is that, and I quote: "Ofsted does not know whether its school inspections are having the intended purpose: to raise the standards of education and improve the quality of children’s and young people’s lives."

This conclusion raises an obvious question: if Ofsted cannot demonstrate that it is improving standards of education, then what is it for?

Ofsted is a key player in a school accountability system that is driving teachers and school leaders from the profession, exhausted by stress and excessive workload. And teacher shortages are now possibly the major factor that threatens standards of education in England. Questions on whether Ofsted can reform itself and remain in existence must be seriously asked.

The problem, according to the NAO, is that while Ofsted’s remit has been significantly expanded, its budget has been cut by 40 per cent – in order to keep within its budget, and in response to a shortage of inspectors who leave because of excessive workload and dissatisfaction with the job (interesting parallels between inspectors and teachers here). Ofsted has, the NAO concludes, "struggled to meet the timescales set out in its inspection framework" and has failed to meet its target, even for re-inspecting schools previously graded as "inadequate", the highest risk category.

Lack of engagement

As the periods between inspections lengthens, so the inspection process has also changed, as short inspections for schools rated "good" have been introduced by Ofsted. The NAO reports that this has caused dissatisfaction among Ofsted inspectors, who report that they have less time to engage in school improvement work.

And, in a really quite extraordinary admission, Ofsted told the NAO that "the introduction of short inspections had also made inspectors’ jobs more about checking compliance and less about improvement and follow up work".

All of which contributes to the NAO’s conclusion that "as a result of the decisions by the Department and Ofsted, the level of independent assurance about school’s effectiveness has reduced".

In another startling finding, Ofsted reveals that one in 10 of its school inspections do not meet its own quality assurance processes – an admission that only confirms what school leaders and teachers tell me repeatedly: namely, a school’s inspection outcome depends far too much on the quality of the inspection team that walks through their school gates.

Ofsted is at a watershed. It is highly unlikely that the government will reverse the spending cuts it has imposed on the agency. 

The watchdog will not get more funding, its short inspection framework is largely about compliance and not about school improvement, and it's unable to assure the quality of its inspection processes and judgements.

Now is the time is ask this fundamental question: are there other, better, ways to inspect schools?

My answer to this is yes. And I get the impression that this once deeply unfashionable view is gaining ground both within the government and throughout the education community.

Mary Bousted is joint general secretary of the NEU teaching union. She tweets @MaryBoustedNEU