The latest batch of government statistics provides another feather in the cap for Jewish schools.

As we reported last week, five Jewish schools appeared in the top 50 out of 6,530 state schools in England for Progress 8 — the score which measures how much progress children have made from year seven to GCSE.

Almost all state-aided Jewish secondary schools ranked “well above average” or “above average”, according to provisional figures published by the Department for Education.

Collectively, Jewish schools achieved an average Progess 8 score of 0.83. To put that in context, a score of 1 means that children achieved a whole grade better at GCSE, in English and maths and six other subjects, than might have been predicted when they first started secondary school.

It is a result which reflects well on the calibre of their teachers.

But invariably someone will argue that the bare data doesn’t tell the whole story because many Jewish schoolchildren get the extra benefit of private tutors.

So how much tutoring goes on? As far as I am aware, there has been no study of its extent among pupils in Jewish schools. At a dinner party, one guest told me she heard of a girl at one school enduring a batter of four tutors on a Sunday, but I doubt whether that’s par for the course.

Two years ago, a report by a charity, the Sutton Trust, which described private tuition as the “hidden secret” of schooling, calculated that a quarter of children in state schools in England and Wales had a tutor at some stage in their educational career. That figure rose to 42 per cent in London.

Privately educated children were twice as likely to have a tutor as those in state schools. Two out of five state school teachers earned additional income through giving private lessons. Tuition, said the charity, appeared to be growing.

But how much exam grades are boosted by the receipt of private tuition is impossible to tell. The P8 scores of Jewish state schools indicate that children are achieving almost a grade better across a variety of subjects than expected from their educational level at age 11. It is unlikely that most of the children who gain a helping hand from a tutor do so in more than one or two subjects. And then some may simply have a bit of coaching in the run-up to GCSEs, while others may be a tutored over a far longer period.

Of course, schools amount to more than their annual exams returns. Ofsted’s chief inspector Amanda Spielman recently acknowledged the inspection service had placed “too much weight” on exam results and said it would in future try to use broader criteria to assess a school’s quality of education.

Too much focus on performance data led to too little thinking about the curriculum, she argued.

But exams still matter and, as long as they do, parents will continue to pay — if they can — to enhance their children’s prospects.

It would be interesting to know the proportion of children at Jewish schools who do receive private tuition — and how much they actually get. Somehow, I doubt that schools themselves will rush to commission such research.

But an enterprising postgraduate education student might take up the challenge as a topic for a thesis or dissertation.