Hello, @vcfromhk
I am writing as a former admissions tutor at an ‘upper’ Russell Group English university. (For those who don’t know, the RG is comprised of the traditional research-intensive universities. Although I have some issues with this and find it no longer valid, belonging to the RG is considered prestigious.)
A number of my personal tutees have been Oxbridge rejects, and they are mostly highly academic. Even for the best students, Oxbridge admission has a big element of luck. The best thing you can do for your DD is to broaden her horizons.
I do not at all mean that you should actively quash her dreams. But encourage her to live in the real world. English at Oxford requires AAA at A levels (most will do better) and a suitable mark on the Oxford ELAT exam. At Cambridge the standard is A star AA and a good mark on the 90 minute interview essay.
FWIW, in my STEM discipline the Oxbridge internal exams kill off many an otherwise promising application.
Your DD’s teachers and GCSE marks will give you some sense, well before Year 13, of how realistic an Oxbridge application is. I agree your DD’s maths is irrelevant to an application in a Humanities field.
Your user name raises the possibility that you are from Hong Kong? I believe that Asian parents sometimes downplay their children’s accomplishments in public. I find this refreshing, but it means we don’t really have a sense of your DD’s abilities, except that like most she isn’t an academic superstar.
Personally I would keep her in the Outstanding state school. I would encourage her to continue her personal and academic development in a wholly positive manner and let the chips fall where they may. Best wishes to your family