I’d imagine all academic schools have criteria for taking A Levels generally and also in specific subjects.
As far as I’m aware with RGS, they want 7s in the subjects to be taken at A Level. I think they offer a course for anyone who wants to stay on - but yes, if someone hasn’t got a 7 on an A Level they fancy, then there will be a more limited choice. Isn’t that the same at Caterham or the Cpllege or St Bedes? All set minimum requirements....but what they are might differ.
A small no each year do a bespoke course in 6th form - so not the standard 3 A levels, but perhaps 2 and some other things too, with a view to perhaps doing a 3rd A level in a 3rd year. So I don’t think people are turned away. However their choices will be less with less good GCSES - perhaps those with a 6 might go to the College to continue that subject at A level because they really want that subject. Given most grades at RGS are 7/8/9 by far, most parents and kids would like the idea of students of similar ability in the class so progress can be rapid -a 6 is very different to a 9.
In my view it’s always hard being academically at the bottom in selective schools. Being on for a 6 would be considered very decent in most places but you can decide you’re not bright at all if your mates are on for 8s and 9s.
I do think all schools set criteria though for the next stage. None have free entry to A level from any starting point. And I don’t think many schools manage out now - it’s v unpopular - they will offer a course, but a limited choice to weak students. I think RGS says they want students to be ableto get a B minimum at A Level and the unis they target rarely include Cs in their offers. Bs at A level are not so likely from 5/6 at GCSE.
I know kids at both and families seem happy with both. Caterham seems more traditional and the boarding does add something for all children whether boarders or not. RGS seems to be having students from further afield now - good numbers from Guildford who want co-Ed academic instead of single sex.
Dunnottar seems to have been a big success - giving a decent independent option to those who don’t get Caterham or RGS - and from what I hear, equal numbers go there (Dunnottar) and to RGS from schools like Micklefield or Hawthorns these days. Seems like RGS and Caterham are harder to get into these days but D has been a good alternative.
In the end, either C or R will give a good education. At RGS 90%+ of A levels have been A*-B for about 6 years now and I think it’s about 85%+ at Caterham. Shorter distance could be the decider. I’ve known lots of parents at Hawthorns which is perhaps placed midway with parents living nearer one or other - there RGS has been seen as harder to get into over last few years with some getting C and not R more than other way round. Some seem to feel C is more relaxed academically.
Given they are similar in results and lots of ways too, short journey and perhaps child preference might be good things to go on - as it’s very marginal, you end up choosing based on such tiny things like who had the best coffee, or which Head said one thing you didn’t like otherwise!