An outcome for those who are interested.
I chose a gentle, incremental approach to the school choice issue. Emphasised that that it was her decision all along but encouraged her to be open minded, to go to the open day and the additional activity day. She did with a bit of protest and under the promise of some bribery!
Then in November she suddenly said she wanted to do the entrance exam "to give herself options" which flabbergasted me. We did one afternoon of practice papers which prompted some more tears. She went in to the exam, white as a sheet, but came out laughing.
She was offered a place, spent about three weeks thinking about it before deciding that, mainly because of the sports opportunities, she wanted to go.
She is feeling sad about leaving her friends, no question.
Ironically, since my first post about her being unconfident and quiet in school, she's become much more confident in her abilities and willing to put herself forward in school and group situations. So I think she probably would have been okay in the local school, although the more I hear about the local school the more glad I am that she chose the other one.
Every child is different but I genuinely think that for her, this was the right approach.
Thanks to everyone's input, it was really appreciated.