Ofsted has been clear for months that is serious about tackling off-rolling.

The inspectorate has led the way in trying to quantify the problem of schools informally excluding pupils to boost their figures.  

The idea that schools have become so focused on their league table scores that they look to lose pupils shows, in chief inspector Amanda Spielman’s words, that they have “clearly lost sight of the purpose of education.”

Ofsted has also provided a definition of off-rolling: “The practice of removing a pupil from the school roll without a formal, permanent exclusion or by encouraging a parent to remove their child from the school roll, when the removal is primarily in the interests of the school rather than in the best interests of the pupil.”

And the figures the watchdog has unearthed do suggest a clear problem.

Inspectors found 19,000 children dropped off school rolls between January 2016 and January 2017, and around half of those students did not reappear on the roll of another state-funded school.

It has also identified 300 schools with high pupil movement between Year 10 and 11 - which indicates that off-rolling could be taking place - and has vowed to use this data to help decide where and when to inspect.

If off-rolling is happening, then schools can expect to be failed under Ofsted’s new inspection framework. And Ofsted has also begun to identify off-rolling under its existing inspections. 

Last month, Tes revealed that two reports identifying off-rolling had been published, which placed the schools, Salford’s Harrop Fold (of Educating Greater Manchester fame) and Shenley Academy in Birmingham, into special measures.

So far so clear.

But then, as Tes revealed last week, came the third report for Discovery Academy in Stoke-on Trent.

The report starts: “This is a good school.”

But the next sentence reads: “Leaders have transferred pupils from the school’s roll during Year 11, when this was not in the pupils’ best interests.

“This constitutes off-rolling according to Ofsted’s definition.”

It is hard to imagine a more striking juxtaposition in an inspection report. This is not a case of inspection teams failing to realise the aims of the centre - because we are given to understand that Ms Spielman was involved in the signing off of this report.

Ofsted has made the fair point that it is not unusual for inspectors to find good and bad practice in the same school and it should report on both.

The findings about off-rolling sit alongside an otherwise glowing positive report.

The other obvious point to make is that this school was inspected under the current framework while the tougher stance Ofsted is set to take on off-rolling will come into effect from September.

However, the situation today is that Ofsted has sent out a very mixed signal about off-rolling and how serious a problem it is.

After promising to clamp down on the practice it has judged one of the first schools it has found to be guilty of off-rolling as “good”.

Part of the problem may be that despite Ofsted’s definition of off-rolling, there are still differing views on what exactly is meant by the term. 

In the case of Discovery, it was found to have moved 10 Year 11 pupils onto the rolls of what Ofsted described as “good quality alternative providers”. They were not being home educated and had not disappeared from the system.

Sarah Robinson, chief executive of Alpha Academies Trust, which runs the Discovery Academy, is adamant that their move took place as part of a local authority-wide agreement and had a “negligible effect” on the school’s league table score.

“We have not lost sight of these pupils,” she insisted, saying that moving them onto the rolls of alternative provision rolls in their GCSE year was “about providing clarity for who was accountable for them”.

Some may still be suspicious of the motives involved. But this is hardly the same as a school persuading parents to take difficult pupils away and washing its hands of them.

And as Julie McCulloch, the director of policy at the Association of School and College Leaders argues: “There needs to be recognition of the fact that there are genuine cases where it is in the pupils interest to move from one school to another or from one school to alternative provision.”

If Ofsted really wants to make a difference on what can undoubtedly be a very insidious and damaging problem then it may need to be more precise in its definition.