Jill's gymkhana
By: Ruby Ferguson.
Edition: Rev. ed.
Series: Jill -- 1
Publisher: Hodder Children's Books
Published: 1996
Place of publication: London
Language: eng
Number of pages: 155
Notes: Originally published: London : Hodder & Stoughton, 1969.

1996 edition published with Hodder Children's imprint.

I have a copy published by Brockhampton Press with no actual publish date. 

The author died in 1966, so therefore I believe the first publish date would be earlier than 1969.