The correct medical term for this debilitating condition, now afflicting most of education, is "distinctivitis", acute inflammation of the desire to step out of line. It is more popularly known as the "curse of the norm".
If someone produced a rank order of different schools' expenditure on paper, where would you hope to be? At the top (you incompetent, feckless wasters)? At the bottom (you do not even care whether your pupils have the right materials)?
Or safely in the middle? Phew, what a relief. We are average.
Even to excel you need to aim at the median. Keen to do well in local or national primary school league tables? Make sure every single pupil gets a level 4 in the Sats, no more, no less. You score 100 per cent in the "level 4 or above" category and come top of the national league table.
It is the same in a secondary school. Ensure every pupil achieves five grade Cs at GCSE, no better, no worse. If necessary, devise a special GCSE in hopscotch that counts as five subjects. Congratulations on being the best school in the land with 100 per cent in the "five A* to C" class.
It is the ultimate curse of a crude system of control, grounded in two severe blights: over-reliance on rank ordering of what is most easily measured, rather than what counts, and the culture of compliance that goes with it. It produces "borderlining" - much attention for children at critical 3-4 or C-D borderlines.
Yet distinctiveness is our national hallmark, the reason we produce so many Nobel prize-winners, inventors, artists and thinkers. Why should every girl in the country be called Norma and every boy Norman, in the land where Norm is king?
For anyone who does not believe this, wait until the Sats results come out.
When national testing was first introduced for seven-year-olds, the assessment was constructed in such a way that the average child would achieve level 2.
It was no surprise, therefore, that about half of children gained a level 2, while roughly a quarter reached level 1 or level 3. So far, so good.
Just the sort of normal distribution that the test designers had planned.
Unfortunately several disasters followed, setting the scene right up to the present day. Newspapers screamed headlines about a quarter of children being below average (er, actually it's more like 49 per cent, on any normal distribution you care to name).
Much more damaging, the Mail on Sunday ran a front-page story saying that nearly a third of seven-year-olds could not recognise three letters in the alphabet. This was completely false, based on a misunderstanding of national curriculum levels.
The "third" was actually the 28 per cent of children awarded level 1 or less, almost all of whom were perfectly capable of recognising three letters of the alphabet. The true figure turned out to be one child in 40, that is, those not even at level 1, rather than one child in three, but it was months before this was revealed.
Meanwhile, Kenneth Clarke, secretary of state at the time and as assiduous a pursuer of truth in education as the average drone, gleefully used this manifest falsehood to beat schools to a pulp.
At the age of 11, the average child is supposed to be bang in the middle of level 4. Just see what happens when the Sats results come out. Probably 75-80 per cent will achieve level 4 or better.
I confidently predict that the man with the wooden head, among others, will assert that a quarter, or a fifth (or "a third" in the more innumerate newspapers) of children have not reached the expected standard.
What started off as the average has now become the expected. Soon every adult in the land will be expected to be of average height or more. One centimetre less and you will be taunted as a midget.
Even worse, the really idle journalists and commentators will say that a quarter, or a fifth of children, leave primary school unable to read, another blatant lie.
Similarly, when GCSE results are published, the emphasis will be on "nearly a half" failing to get five GCSEs at grades A* to C, when back in the much-longed for "good old days" about 80 per cent did not get five O-levels or better.
Distinctivitis is curable, of course. And fortunately many teachers and heads know this.
Just utter the Old English secret magic word "buggerit". Suddenly the Qualifications and Curriculum Authority schemes of work spontaneously combust, Ofsted inspectors turn into toads, the fetters of compliance fall away, and the joy returns to teaching.