Sue, this is wonderful!
I love the horse-knowledge that is so central to the character of George. It takes it above a simple narration and builds (in me, anyway) massive curiosity about the details of coach-driving life. I find it fascinating, not being a horsey person myself.
Your writing technique and skill is evident, of course. the pace is slow enough to allow the characters to broaden pleasingly, but also keep it the curiosity of where it's leading right up there at the front, driving it on (forgive any horse/coaching/driving puns-it's an affliction
) so that the reader doesn't even notice that they are being led through the story and being given chunks of the future, and the character's pasts as they go.
The originality of it certainly rests with the knowledge and in-depth detail of true horsemanship: the use of the reigns, the training, the different whips, the healing time needed for horse wounds... etc but I think setting it in the 1800's adds to the atmosphere and gives a certain sentimentality, without it becoming sentimentalised.
It's very engaging and wonderfully written. I thoroughly enjoyed it and look forward to more!