Here's a few of the books on offer:
Firstly some by classic equestrian authors. There's Henry Wynmalen's Dressage (a tome much followed by the Pullein-Thompsons. Wynmalen had a major influence on how they taught riding and schooled horses, and on the instructional nature of their own books). This is a decent copy, and it's now £3.60.
Another Wynmalen, this one's a dustjacket-less copy of Horse Breeding and Stud Management. Not, as far as I know, used by the Pullein-Thompsons. SOLD
Waldemar Seunig's texts were translated and published both by J A Allen and Robert Hale. This copy of Horsemanship is published by Robert Hale. It's a decent copy, and it's now £3.60.
Now £30, a history of Scotland's native horse, by R W Beck. It's a survey of the Eriskay Pony. Not many of them around now, alas.