Class sizes down! Teacher numbers up! Complaints down! Results up! No, this is not the latest list of impossible targets issued by the Department for Education and Skills; it is, in fact, a very brief summary of the latest edition of the Independent Schools’ Census, a sort of Good News Bible for the private sector.

According to the census, published by the Independent Schools Council, those of us working in such schools have never had it so good. We are told the pupilteacher ratio is at an all-time low (one teacher for every 9.87 pupils); that more of our pupils than ever before are going on to higher education; and perhaps most surprisingly that it is getting cheaper to send Jasper and Jemima to these citadels of academic excellence.

OK, so the average fee for a boarder is around pound;19,000 per annum (without extras), and, yes, the increase last year was an eye-watering 5.7 per cent, but the ISC is at pains to point out that this is “the lowest fee rise in seven years”. Also the number of pupils with fee assistance has reached 24 per cent. So what are you complaining about? We’re doing ourselves a disservice, guv’nor: we’re practically giving it away!

Furthermore, The TES recently reported that state-school teachers are leaving to join the private sector in ever-growing numbers. The report said that “the shift was put down to smaller classes in private schools and the opportunity to teach specialist subjects” (“Teachers flee to private schools”, TES, May 12).

A total of 1,870 teachers left the state sector to work in private schools last year, with 608 moving in the opposite direction. And who can blame them? If things are so great, why don’t more leap over this educational Berlin Wall and join us in our sun-dappled quads? Well, it could be because this view of private education is misleading, to say the least.

Class sizes are indeed smaller than those in local comprehensives, but the census reports that this is an average and so will include, of course, those specialist subjects such as Latin, which may have classes of one or two pupils and are retained by schools rather as if they are trophies as much as anything else; it is more common to teach classes of about 23 or 24 in a private secondary school.

Numbers in independent schools are undoubtedly increasing, but many of these are being recruited from overseas; the domestic market (which, incidentally, also includes many “overseas” students who are resident here) is stagnant.

It is disingenuous of the ISC not to link the need for wider recruitment with high fees. The number of pupils receiving help with their fees is also up, and the figures are outwardly impressive: the equivalent of pound;286m is provided as assistance with fees. Two things need to be remembered here, though: first, the contribution made by the school can range from the very significant to a more tokenistic “incentive” of a few hundred pounds; also, independent schools are very aware that the Government is constantly reviewing their status as charities and help with fees counts as charitable aid. There might be a link.

And what is it like for the teachers already working in the independent sector? In the current slap-on-the-back atmosphere, I read only one discordant voice: Mary Bousted, general secretary of the Association of Teachers and Lecturers, said of this exodus: “Employers should take no comfort from this ... too many independent schools fail to take work-life balance issues seriously.”

These words will have rung true for many working in private schools: according to the ATL’s latest research, 64 per cent of staff in the sector work more than 55 hours a week and 35 per cent feel that their work-life balance has worsened over the last two years. Many grumble, but most continue to work hard because to do otherwise might affect the pupils and place their own position under threat.

Of course these statistics can be interpreted in many ways as well (are all those who responded to the survey inclined to complain?); but what is obvious is that the document spun by the ISC this month is economical with the truth and, despite its desire to trumpet this sector’s successes, it sounds defensive, shrill and complacent.

If teachers are leaving the state sector in such numbers, then something must be very wrong in maintained schools. However, this does not mean that independent schools are somehow superior, and it is certainly not a cause for self-congratulation; indeed, it is a modern tragedy which shames us all.

The day when teachers no longer feel driven from one sector, or trapped in another, will be a day for real celebration because perhaps only then will we be able to represent ourselves truthfully instead of relying on dodgy dossiers and a tendentious use of statistics.

Dr David James is head of English at Haileybury, Hertfordshire