At last, after some seven weeks of our new government, we have a definition of a “coasting” school. That’s the good news. The bad news is that hundreds of schools will be swept into this category and could be turned into academies. What’s worse is that they probably won’t be the ones that need to improve.

All three of the last administrations - Labour, the coalition and now the Conservatives - have threatened to tackle the problem of schools that don’t do as well as the ability of their intakes suggests they should.

Unfortunately, the government’s new measure will, initially at least, fail to confront this problem. This is because, at the outset, schools with more than 60 per cent of pupils achieving five good GCSEs, including English and maths, will automatically not be considered coasting. This will not change until 2018, when the raw attainment element of the “coasting” definition is replaced by Progress 8. 

In effect, this means it will be impossible for grammar schools to be considered to be coasting, even if they actually are. Owing to their selective nature, all have at least 78 per cent of pupils achieving five good GCSEs. This lets them off the hook, just as it does with other “coasting schools” benefiting from an affluent middle-class intake.

This is backed up by research from Education Datalab, which shows that the schools deemed to be coasting will predominantly be in disadvantaged parts of the country, even after 2018. This prompted Lee Elliot Major, chief executive of the Sutton Trust, to tell the scrutiny committee for the Education and Adoption Bill this week that institutions in disadvantaged areas should have a specific progress measure.

So what we have is a messy, temporary and unfair measure that will fail to deliver the “real social justice” claimed for the Education and Adoption Bill by education secretary Nicky Morgan. 

Ultimately, the changes will give ministers the right to turn these so-called coasting schools into academies if they fail to improve. Yet if the government truly believes, as it seems to, that academy status is the answer to all its educational woes, then it should have the courage of its convictions and, as many across the educational spectrum have privately said, make all schools academies in one fell swoop. 

There is, of course, little evidence that academisation improves results, underlined this week by the results of a study by the National Foundation for Educational Research. More importantly, the argument is now a distraction standing in the way of getting on with what we know does work.

There is plenty of evidence that good teaching and teachers improve outcomes for children. The quality of teachers has more impact than any other factor, according to Andreas Schleicher, head of the Programme for International Student Assessment, whose data also shows that the most important variation in quality isn’t between schools but within schools.

So let’s not waste any more time with these political contortions; we all know the direction of travel so let’s get it over with. We can then turn our attention to the business of what really matters: improving the quality of teachers and teaching in every classroom.

Read more in the 3 July issue of TES. You can read it on your tablet or phone, or by downloading the TES Reader app for Android or iOS. Or pick it up at all good newsagents.