I was too young to see Stroller in action but heard of him. He was a pony - 14.2 hands - who was re-registered as a horse to compete with horses in showjumping. Apparently he was brave and a great competitor.
At this time jumping was the preserve of cavalry officers and Marion Coakes, Mould when she married, was one of the earliest women in the top of the sport. She was British. Others were Pat Smythe and Iris Kellett (Irish). However the other women went on to ride many good horses whereas I never heard or saw more of Marion after Stroller retired. It's quite possible that once married she settled to a domestic life.
Another small horse competing around the same time was Dundrum ridden by Tommy Wade (Irish). Actually it puts small horses at a big disadvantage, not just because of the height of the fences but because the striding between fences is measured carefully and assumes a sixteen-hand or so horse.
This book is valuable for a look at the times and the arrival of women into the competitive sports, and will be enjoyed by horse lovers.