Indeed difficult to decide also from the very opposite comments here.
We also hired an educational
Consultant who said that FH is more academic in the sense that prepares the pupils better for exams, makes them more "crunchy", but that also GH is very good and still academic. GH have apparently a well established reputation in the school environment and the new headmasters are planning to improve the academic side of both girls and boys sections. She said that Schools like hill house or Knightsbridge school would be indeed easier and less academic, but comparing GH and FH both are good from am academic perspective.
Other than this she mentioned that FH apparently is more looking for boys who can sit still and indeed you need to agree with the headmasters.
I then asked to a friend who is professor at Oxford and she advised us to choose GH as it has a wider curricula and does not focuse only on English and math, wherever these are the subjects kids are assessed with at the seniors schools
Also, GH is where the kids of our nursery headmaster are attending, so also this tell something as the nursery is made of 3 sisters and it is well know in the area.
About the kind of families attending: It is true that at FH o noticed more grounded families in the sense of a lot of busy working mum, but I also noticed a lot of very competitive American and Indian mums at FH (couple told me they are "of course" tutoring their kids, and we are talking of 4yo...).
On the other hand the mums heading to GH from our nursery are all rather grounded as well.
Personally, we do not consider relevant the kind of families as we will have to teach him to deal with much more wealthier family in any event as in this part of London there will always be someone wealthier.
We still have couple of days to decide, at the moment we are more attracted to GH as it feels safer (our kid does not sit still) and facilities are indeed more attractive, also he is very much into music and art, but because of the labels these school have, putting down FH feels not catching some opportunities for the kid to deliver better results at the exams.