Burke, London, 1962 , illus Barbara Crocker
Dragon pb 1967 and 1970s
Goodchild hb 1986
A gang of motorcyclists are up to no good with the ponies, and one day frighten them all away apart from Frosty and Turpin.
Riding School Trilogy
The Empty Field
The Open Gate
The Doping Affair (later published as The Pony Dopers)