D A Young (Derek Anderson Young) wrote just the one pony book that I have been able to find. It is unusual in being illustrated in colour throughout, with colour plates and a frontispiece by Maurice Tulloch. It’s a pity the author didn’t write more. This story of a family hugely excited by the prospect of a summer holiday with ponies, which then fizzles when they meet the teenage heads of the local riding club (drunk with power, in my opinion) is a well observed story of the wielding of power, and of how easy it is to misinterpret what people do.
Finding the book: Ponies in Secret is becoming harder to find, and more expensive.