Meyler, Eileen

Eileen Meyler wrote a series of seven books about the Elwood family, of which Adventure on Ponies is one. None of the other books, as far as I know, have very much pony content: Johnnie and Prue and their adventures are at the heart of the series.

The Elwood Family Series
Adventure in Purbeck
Adventure at Dale House
Adventure on Ponies
Adventure Next Door
Adventure at Hawthorn
Adventure with Whim
Adventure at Tremayne

Finding the book
Easy and cheap to find in both its incarnations.

Sources and links
Children’s Series Fiction, NCC, 2004