kayah,
I kind of abused the stats, but they have their logic too.
I read on this site that at one top grammar, 47% of kids are privately educated. Yes this was a case 1y and 3y ago, but less so.
So this explains how you can kind of forget 60 places that normally mostly would go to everyone - but this year will go to totally overprepared pivate prep school kids who would have gone to good public schools but their parents cannot afford the fees, leaving the rest of kids fight for remaining 70 places for the "commoners".
Lets face it that the amount of tutoring that the kids from prep schools receive is crazy, both at school, and at home. You cannot possibly compete with this at state school, unless you take you child home for home education, as at state schools once your child reaches stage 5 on KS2, he or she bascailly wastes time in class, as the school is much more concerned on helping grade 3 and 4 students to reach grade 5, as this is the measure on which they will be judged later. Painful, but true.
The irony is, that this might actually devalue the quality of grammars in 7 years, as more over prepared kids will get in vs naturally able ones. One poster somewhere interestingly noted that at his grammar the most stupid kids came from private schools.