Dear Yummy Mummy
As the Bucks 11 plus has very little to do with the national curriculum, the amount of passes is NOT an indication of a 'good or bad school'
There are many arguments....
Affluent areas are more likely to have parents who can afford private tuition, in addition the parents may have the money and the knowledge to home tutor [ DIY ]
My own childrens junior school, excellent school with many good points. My daughters class over 2 thirds of the class passed [ an extremely bright cohort, the handful that went to the uppers scored highly in their GCSEs] The following years saw a marked difference in children passing down to 12, then 9 then 8.......same school, same teachers, different children.
So, your school has little bearing on the number of children passing, its more likely down to parents gathering information, using a tutor or DIYing....
Please also bear in mind that Bucks state schools are NOT allowed to coach for the 11 plus, in any shape of form. Private schooling is another matter, they have more freedom in teaching VR skills. I know of one local independent that interviews the parents of year 5 children to ascertain whether the child is going for the Berks/Bucks 11 plus OR a common entrance exam.......the chidren are then split into classes accordingly for the teaching/coaching of the exam.
I do understand that not ALL private schools coach, the ones I know, do.