British Library. Those editions are:
Besides finding information about this mysterious George Mills, I want to read all of his books. For a start, I've already received:
King Willow; Spring Books, London; printed in Czechoslovakia, Undated. [Illustrated by Tom Thursby]
I ordered it from Paperbackbookshop.co.uk Ltd., in Gloucestershire on 6 February, 2010, but it was shipped a prior from a P.O. box at the Brussels Airport in Belgium/Belgique/Belgie. My wife, Janet, ordered it for me, so I don’t actually know what it cost. It arrived on 25 February. The dust jacket lists it as a title in Spring Books' "Fanfare Series" for youths. It’s 256 pages and contains no copyright date.
This doesn’t appear to be a copy of either of the two editions of King Willow available on the shelves of the
King Willow, etc.; G. G. Harrap & Co.: London, 1938.
King Willow (New edition); Oxford University Press: London, 1951.
If anyone out there has any idea of the publication date of my undated 'Spring Books' edition, about the seemingly-defunct publisher [Spring Books], about Mills himself, or about the illustrator [Thursby], I certainly would appreciate the information!