I've been reading this thread and think the exam results are important, and schools such as GHS, RGS, and Tormead should be given credit for their very good results. However, I think this thread is treating one GCSE figure as a more comprehensive measure of a school than it actually is.
As highlighted, the table mentioned above is not actually comparing the same thing in all cases, since some schools are listed using 9–8 grades while others use 9–7. More significantly, % 9–7 is an attainment figure and does not show how much a school has added. Schools have very different intakes, so comparing a highly selective school directly with a broader-ability or non-selective school only tells part of the story.
Cranleigh is a good example. Its figure of 71% was described as rather uninspiring, perhaps because of its strength in Drama and Humanities, but its 2026 results showed 80% of grades at 9–7 in STEM and 85% in Humanities. I also don't see why performance in Drama should somehow count less; one of its productions was chosen from around 300 schools to perform at the National School Theatre Awards in the West End, where one of its students won Best Actress. That seems like a pretty significant educational achievement too.
Priors Field is another example. It is non-selective, but nearly 20% of GCSE grades this year were Grade 9. Its higher-tier iGCSE Maths top set also achieved 100% grades 9–7 this year, with half at 8–9 and 31% at Grade 9, with many then moving onto Further Maths. Outside exams, a student was national champion at this year's Young Fashion Designer UK final, another was Highly Commended, and this now makes three consecutive years in which Prior's Field students have won at the competition. A younger student was also runner-up this year in a separate Graduate Fashion Foundation competition.
I'm sure you can find equivalent examples at other schools in science, music, drama, sport, debating, art and more. That's really the point. None of these examples proves one school is better than the others, just as a lower 9–7 percentage doesn't prove the reverse.
For the OP's situation, I would want to know much more about how children starting from a similar point progress, what kind of learning support is available, whether they gain confidence and what opportunities they have to discover what they are genuinely good at.
Exam results are part of the picture, but a GCSE percentage can't capture the whole picture. Any one figure is bound to simplify something much more complex, and relying too heavily on it risks undervaluing schools that serve different children well or excel in different ways.