The Little Grey Men

From Author Wars - https://authorwars.com/publications/the-little-grey-men-412172.html

Overview:

Title: The Little Grey Men
Author: BB
Year: 2004
ISBN-10: 0192719467
Publisher: Oxford University Press
Pages: 256
Binding: Trade Paperback
Type: Novel
Title Reference: The Little Grey Men: A Story for the Young in Heart
Notes: Data from Amazon.com as of 2013-03-16.

This is not the Oxford Children's Modern Classics edition (Amazon 2013), but the following smaller and cheaper edition. Expected: 20cm, £3.99 or 4.99