When I became a headteacher, I was invited by the Independent Schools Inspectorate (ISI) to become an inspector. This required an extra week or two’s work each year. However, the benefits far outweighed the disadvantages; seeing other schools at work enabled me to bring back examples of good practice and to be ready for inspection myself.

After I retired from school, I started a second career as an inspector. The Ofsted and ISI frameworks are very similar – except ISI inspections report on boarding and devote more space to extra-curricular activities. However, until this week there had been one significant difference: Ofsted awarded a single-word headline judgement of the school – Outstanding, Good, Requires Improvement or Inadequate. ISI inspections abandoned that headline many years ago.

There are two problems with the headline grade. First, some very good schools were caught out because of rushed administration. Inspectors are very hot on safeguarding – and quite rightly so. However, a school might appoint a new member of staff quickly to fill a gap, but slip up on some of the important recruitment checks. There may be no real danger to children, but such an error would cause the school to be down-graded to Inadequate – even where pupil achievement was first rate. Under the new system, such a serious failure will be highlighted, but the school spared the ignominy of the inadequate grade.

There is a further distraction of the single grade: nationally 17 per cent of schools are graded as Outstanding and 71 per cent as Good – a total of 88 per cent. We can celebrate these figures, which reflect a country with high education standards. However, only 50 per cent of schools can achieve average or better exam results; which means a significant portion of ‘Good’ schools are achieving below average results. In some cases, a ‘Good’ school’s results are far below average. So, rather like the curate’s egg, some good schools are only good in part!

The headline grade sums up what a school does to keep children safe, their personal development, their behaviour and the quality of education. Therefore a ‘good’ grade can be awarded even though some aspects of the educational provision are of concern. For example, these comments have appeared in ‘Good’ Ofsted reports: “The sixth form requires improvement”; and for another ‘Good’ school – “The most able pupils are not challenged, so they do not make rapid progress.” While the first school does many things well, they are not delivering for their sixth form, and in the second example bright pupils are making slower progress than pupils of similar ability in other schools.

On the other hand, these are the sort of comments that can be seen in an ‘Outstanding’ Ofsted report: “Students make rapid progress. A well above average proportion of students achieve the highest grades. Staff empower students to take control of their own learning and they rise to the challenge because they are extremely keen to succeed.” In that school, pupils are making faster than average progress and their results are enhanced because ambitious pupils work very hard on their own. In schools with the best results, A-level students usually work for a minimum 15 hours a week on their own, reflecting the Ofsted framework of being resilient, confident and independent.

As Bridget Phillipson, the new Education Secretary, observes: “Single headline grades are low information for parents and high stakes for schools. Parents deserve a much clearer, much broader picture of how schools are performing.”

Thanks to this week’s change in Ofsted headline judgements, in future we will be able to read report cards which summarise what a school does well and what it needs to do to improve. We must get past the veneer of a single word judgement and read the whole report.