The Grey King

From Author Wars - https://authorwars.com/publications/the-grey-king-291363.html

Overview:

Title: The Grey King
Author: Susan Cooper
Year: 1984
ISBN-10: 037030828X
Publisher: The Bodley Head
Pages: 174
Binding: Hardcover
Type: Novel
Title Reference: The Grey King
Notes: {{PV|Willem H.}}'s copy has no dustjacket, so no price information, cover artist etc.
ISBN on the copyright page is stated as 0-370-308281-X, but eleven digits is too much. Google search for 037030828X has results.