A few weeks ago, I thought Ofsted was really in trouble.

A rush of criticism from some of the biggest and most politically influential Multi Academy Trusts (MATs) about the new inspection framework seemed to be landing in schools.

But then the momentum dissipated. A couple of big MATs came out strongly for the new regime, and chief inspector Amanda Spielman’s confident launch of the Annual Report looked to have put this behind them.

Now, I’m not so sure. There is seemingly some ongoing nervousness in the Department for Education and No 10 about this fight, and they are seeking ways to resolve it. 

And then came the #PauseOfsted campaign that urges active school leaders against being part-time inspectors - this has the potential to be a game changer.

To be clear, I don’t agree with the campaign. Like the Association of School and College Leaders, I think that any inspectorate is worse if it doesn’t have serving school leaders working as inspectors. I also don’t have sympathy with those who want to abolish Ofsted altogether, many of whom (with honourable exceptions) are longstanding campaigners against all accountability.

I think that Ofsted, while not without its flaws, is a vital part of raising standards in the system, exposing poor practice, and improving equity.

But what is it that unites Conservative special advisers in No10, National Education Union boss Mary Bousted, the Heads Roundtable (a group of school leaders), MAT chief executives, and Govian education reformers? This sounds like the introduction to a bad joke, but the answer, in so far as the future of Ofsted goes, is clear.

It is anger at inconsistency of inspection judgements and the related issue of the quality of inspectors. That’s what was at the heart of the report I wrote for think tank Policy Exchange proposing various Ofsted changes six years ago. And it’s great to see that some of that has happened. Ofsted is narrowing the things it looks at to be clearer to schools. It is offering better training to inspectors. It is clamping down on the various myths which float around and muddy the waters about what Ofsted looks for.

And it has, most importantly, brought additional inspectors in house, and away from the large outsourcing companies who weren’t able to satisfactorily ensure quality and consistency of inspection.

But set against that, a number of things are now happening that threaten the issue of quality and consistency again.

The new framework is undoubtedly more cognitively challenging to understand and interpret. And anything new is always going to take longer to become familiar to those executing it (which is why extending the transition period makes sense). Removing the exemption for ‘outstanding’ schools, while a sensible policy, brings another 1,000 schools in scope which need inspecting. And if the Conservatives’ election commitment to extend inspection times becomes reality, that will place significant additional manpower requirements on the inspectorate.

Ofsted’s budget can - and will need to - increase to cope with this. But having the money isn’t enough if you can’t recruit enough people. Ofsted faces a risk that it will either need to significantly increase the number of serving school leaders applying to be inspectors so that it can recruit at the necessary quality - or increase its in-house HMI capacity.

Neither of those are easy. HMIs earn about £70k a year. Replacing even a fraction of the 2,300-odd part-time inspectors with full-time HMIs would have significant budget implications (although such inspectors are paid, it isn’t as much as HMIs). And if you wanted to recruit large numbers of school leaders on a full time basis - who would have the confidence and curriculum expertise to inspect their peers to the highest quality - £70k isn’t enough to get many experienced secondary leaders, especially to cover London and the South East.

And if #pauseOfsted has even a minimal impact - say a 5-10 per cent fall in the number of serving leaders signing up - then it is likely that the bar for being accepted as an Ofsted Inspector on a contract basis will need to be lowered. If it brings about more than that - an effective partial boycott of the inspectorate - then it has the potential to significantly affect the ability of Ofsted to execute its remit.

I don’t personally think it will get that far. But at a time when inspector quality and consistency of judgement in applying the framework is the single issue that unites supporters and critics of Ofsted alike, the policy environment and the #pauseOfsted campaign are respectively raising the number and quality of people needed, and probably shrinking the number and quality of people available.

The inspectorate finds itself in an unenviable position.

Jonathan Simons is a director at the Public First policy consultancy