This year, parents of daughters may also consider the recent report from the Centre for Education and Employment Research at Manchester University, which declares it to be an erroneous belief that single-sex education will somehow get girls higher examination grades. The report says that published GCSE and A-level results make it appear that there is a clear-cut advantage to single-sex education. Surely this is just semantic quibbling, which matters not to parents or pupils.

The first problem for league table readers is decoding them. On Saturday August 26, The Times and the Daily Telegraph carried two different tables.

The Times listed the top six hundred state and independent schools according to the average score of their candidates.

Top of The Times’ list was Winchester College, with an average score of 31.9. But Winchester was sixth in the Telegraph’s list, dictated by the percentage of subject entries graded A or B. Top of the Telegraph’s list, and tenth in the Times, was St Paul’s Girls. Only one mixed school makes it to the top of either list, and that’s Westminster School, third for The Times and fourth for the Telegraph.

Either way, then, the best results are obtained in single-sex schools. But the report suggests that this is simplistic reading, failing to take into account other factors such as the pupils’ socio-economic background and calibre at entry level to the school.

Leaving aside the fact that teachers have long campaigned for such factors to be considered when compiling league tables, including them undeniably takes time, involving as it does longitudinal studies of children from five to 18.

But the tables would be more useful right now if they offered their information broken down by gender.

Male or female achievement is quite obvious in a single-sex school, less so in a mixed school’s results.

What was the average points score for girls at Westminster, for instance, and how many AB grades did they achieve, and how do those figures compare with those of girls at, say, St Paul’s Girls?

If girls do just as well in mixed schools, then how exactly did those girls do, and stop fobbing us off with how all of the pupils did, because that, for the present purpose, is beside the point.

The wise parent will ask the school for even more detail. In my own school, more girls decide to study A-level chemistry or biology than take English or history, for instance.

I would be surprised if that was true in a mixed school, and even more surprised if girls in mixed science A-level classes achieved most of the high grades obtained by the group. So if the school shows statistics for A-level passes in all subjects, they too should be for girls and boys separately.

The problem with research into how anyone did at school is that you cannot tell how any of them would have done if they’d gone elsewhere, because they didn’t. The pupils with the highest grades in the country were in single-sex schools, and that’s that. There is no way of knowing if the same girls would have done just as well in a mixed environment.

Teachers habitually pay more attention to boys in class, ask them more questions, listen to them longer. I know, partly because I’ve read of the research and partly because I’ve done it myself. Boys click their fingers and squeal ‘Missss!’ even when they don’t know the answers. Girls retreat into embarrassed silence even when they do.

When this report acknowledges that some parents fear that boys could have a dominating and disruptive effect on their daughters’ education, chalkface experience tells me they are dead right.

In the end it behoves us all to remember that this report was commissioned by the Headmaster’s Conference Co-ed Group, which has an obvious interest in the movement of girls into mixed schools. Whether their interests and those of girls themselves are quite the same is another matter.

Hilary Moriarty is deputy head of The Red Maids’ School in Bristol, but writes here in a personal capacity