The question may not be how many coasting or failing schools need help, but how many we have the resources to help

Since the Conservative return to power in May, the papers have been full of Nicky Morgan’s promise to get tough on “coasting” schools. Attracting fewer headlines, but still important, was the government’s commitment to convert every school judged to be “inadequate” into an academy.

The Department for Education (DfE) has suggested that this might affect up to 1,000 schools. More than 1,000 schools are eligible now because they fall below exam floor standards or because they have received an inadequate rating (or both). The commitment to get tough on “coasting” schools will add hundreds or even thousands to the list.

If we overstretch ourselves we risk doing more damage

The government has yet to define “coasting”. It won’t be based on Ofsted ratings alone, Ms Morgan has confirmed, though a judgment of requiring improvement may form part of the definition.

So, how many schools should we be trying to help?

The debate about which schools are subject to intervention, or to receive extra support, has always been in terms of how many are failing, or coasting – defined in terms of not hitting a certain standard.

I would turn the question around and ask: at any given point in time, how many schools can we reasonably support to improve? And how can we make sure those schools get help?

There are three main constraints on the number of schools we can feasibly support in any year.

The number of academy sponsors

Are there enough academy trusts willing to take over these schools?

Writing in The Guardian last month, Warwick Mansell pointed out that of the 447 schools rated inadequate, more than one in four – 123 – had failed their Ofsted a year or more ago and had not yet converted to academy status, or been recorded by the DfE as planned for academisation.

If inadequate schools have long been eligible for conversion, and the DfE hasn’t explicitly committed to turning all of them into academies, perhaps because it cannot find enough good sponsors for them all.

The task of boosting the number of academy sponsors has been made a priority of the regional schools commissioners. They need to choose carefully. As Newsnight’s policy editor Chris Cook has shown, there are as many underperforming multi-academy trusts as there are local authorities.

The number of headteachers

We need to find more than 2,000 new headteachers every year just to stand still. These new heads replace a roughly equal split of those retiring at the normal age, those taking early retirement and those leaving, despite being years away from a pension. The government has made it clear that coasting schools unable to demonstrate a plan for improvement will be given new leadership. If headteacher unions are right and recruiting headteachers has become increasingly difficult, they may struggle to find anyone.

The amount of support that Ofsted is able to provide

Given that a coasting school’s existing leadership may be preferable to any available other choices, support from promised “experts” will be crucial. The number of support hours practising heads can give to other institutions is necessarily limited. Hence, England must look again at the collaborative inspectorate model used in other countries. This sort of inspectorate-supported school improvement takes time to do well.

So unless the education secretary can find more money from within the shrinking DfE budget, Ofsted will need to limit the number of schools it works with.

Changing the terms of the discussion on intervention wouldn’t be without controversy, though. After years of talking about failing (and now coasting) schools, the question will inevitably be asked – why aren’t you helping all failing schools? This implies that the current system is free of risks or downsides. Which it’s not.

Conversion to academy status, even as part of one of the most established trusts, isn’t a panacea. And if we overstretch ourselves we risk doing more damage than helping. Those who really need help don’t get enough, while those on the margin who might improve on their own are destabilised and lose the confidence of staff and pupils.

Additional analysis by Philip Nye at EducationDatalab.