Well DD is a clever girl but I would not say that she is a massive outlier intellectually. She did work hard doing the tutor homework every week and she did try her very best for the exams, which is all you can really ask of a person, that they do their very best!
I and she chose SPGS together as a consequence mainly of the soul-destroying SATs year which both DD and I found very uncomfortable on a number of levels. I did not want her to continue to be a number in a table to show progress, regardless of whether her specific intellectual needs had been met (which they often weren't). I didn't want her to be constrained any more by the national curriculum. I absolutely did not want her to be forced to take eBacc subjects later on regardless of whether that suited her or not. I didn't want her to be a cog in a machine. I think state education is becoming all about data, through no fault of the teachers, and I did want her to go to a school that might teach her to value learning purely because it is actually quite enjoyable!
The exam process for Tiffin and SPGS showed me very clearly that SPGS was much more focused on the whole person and on making the experience comfortable for the child whereas DD felt a bit unpersoned by the Tiffin exam process. This is hard to explain! But she came home from the SPGS exams each time telling me about the nice lady she'd met and the interesting puzzles in the exam and the general fun of the experience whereas she came home from the Tiffin exams telling me that she'd sat for 45 minutes in a huge hall in silence before they could start, she didn't feel happy or comfortable, she didn't feel she was treated as a person. Hope this makes some sense. It's difficult to explain. And of course, it's partly being able to fund the process properly that helps SPGS do it in a kind way, which is no reflection on Tiffin really as they are facing the funding constraints that all state schools are now up against.
Also, DD really wants to do, for instance, Ancient Greek. At Tiffin this means giving up free time to do it at a lunchtime club. At SPGS, it's just one of many options she can choose between. Everyone does two languages, maybe more if wanted later on - there are loads more options for this too, not just French, Spanish and Latin. This is something that will really suit her.
I also liked the curriculum higher up the school which is not just focused on exams but also on broad knowledge and includes electives that bear no relation to examined courses. They were at pains to let us know that they really really want girls to take advantage of all the extra-curricular creative and sports stuff and the clubs etc on offer sound genuinely amazing.
Having said all that, I must add as a disclaimer that I went to SPGS so had confidence that it would be a nice place to spend your school years. I should also say that in fact if we could have guaranteed Waldegrave for DD I am not sure we'd have done the exams, though they were her choice so she might have wanted to do them anyway. And in hindsight, I'd have put Waldegrave above Tiffin on the preference form (though she wouldn't have got it in the first round of allocations or possibly even not until after a term or so). I just felt a bit uneasy about Tiffin. I think it might be a bit of an exam factory. And yes, I know people go on about hothousing at SPGS but having experienced it myself when people were saying the same things I believe that isn't true. I haven't got any personal experience of Tiffin to balance the word on the ground against.
In short, DD and I just thought SPGS seemed friendlier and kinder and had a lot more stuff on offer that DD positively wanted to take advantage of!
Wow, v long, sorry!