As for Miranda hating the countryside but having a horse, I have known people who employed other people to do all that mucky looking after the horse stuff for them, and who only ever rode the horse in a nice clean arena. Poor horse might occasionally have been allowed out for a hack with the staff, but not with its owner. So I can absolutely see that.
I see Miranda as a Dressage Queen. Horse is probably never allowed out of its stable lest it wound its priceless Dutch Warmblood self. Miranda has the sort of boots that cost thousands, and looks down on anyone who doesn't. She has regular dressage lessons with someone very well known, and is the sort of rider who uses a crank noseband, and uses it hard. She probably idolises Anky, and thinks that the halt-that-wasn't-a-halt incident was terribly amusing.
I've just read that back and realised it makes no sense if you are not horsy - dressage judging is a very subjective thing, and there was a lot of controversy a few years ago over the fact that some judging judged people's 'backstory' as well - i.e. if you were very well known and successful, you were likely to do better. The worst incident I can think of is Anky van Grunsven, a massively successful, Olympic medal winning dressage rider whose halt was awarded a very high mark (possibly 10 - can't remember) in a ride when the horse, basically, didn't halt at all.
Boy, have I wandered off topic.
BOOP for Miranda, Lillian and the coffee because I enjoyed that. I am not going to go anywhere near the other story element.