Bisjo I think in an ideal world all schools would have a year-on-year, uniquely computer generated test such as Eton uses but I think it's very, very, very expensive (which is why such a system is not more widespread).
This whole 11+ 'bunfight' has really opened my eyes and made me redefine pushy parenting! We did some 11+ practice papers with DS but as he's not naturally a diligent child he was not an eager student. "Yeah, I've got that Daddy" was the closest you got to an aknowledgement that he was even paying attention. Fortunately he passed and got into a grammar school where he is very happy and whilst not top of the form, he appears to be above average as far as we can tell but it is of course very early days...
But ever since he gained his place, we have had no end of parents from the primary school DD still attends, anxiously asking us how old DS was when we started paying for a tutor (which we didn't) for him. And the looks of disbelief when we say that we didn't even start looking at VR/NVR until six months before the exams. It really, really irks me!
Oh, and whilst DS reports that in his form no-one did attend a prep school (although I do recall the Admissions Tutor said the boys came from about 87 different schools of which about 15 were private sector ones), it is quite apparent that most are from comfortably middle-class backgrounds.
One of DS's best friends has just moved from the state sector to a prep school and it's quite obvious that their whole way of teaching is about maximising the children's chances of getting the places at the schools that their parents would wish them to attend....
I am one of those 'council house' children from the 1950s, 60s and 70s who was lucky enough to get into a grammar school without any encouragement from home or extra help/tutoring.
Quite what has changed that means that the 11+ exams of yesteryear (which did cut across the social divide in measuring intelligence) no longer seem to do so?