Here's something I just found on-line that fills in a little bit more of my timeline of the life of George Mills [my emphasis]:
Author Name: George Mills.
Title: Minor and Major.
Book Condition: Very Good
Jacket Condition: Very Good
Publisher: London. Spring Books.
A very good undated book with a presentation label dated 1962 on front endpaper. Pages browned overall. Extreme bottom edge of spine faded. No measureable wear. DJ is very good, rubbed at corners, rather more at spine ends, a couple of short closed tears.
That's all from Mollie's Loft Books, a bookseller in Pontardawe, Swansea, in the United Kingdom.
It may be no big deal, but with this reprinting of Minor and Major in 1962 [pictured, right, but that's not Mollie's copy], Mills is still drawing upon the popularity of his books well into the early 1960s—and cashing checks attributable to them. Mills would have been 65 or 66 years old in 1962, and hadn't authored a book since 1939.
I had previously estimated the release of the Spring Books impression on Minor and Major to have been in the 1950s, and I had seen other internet sites selling copies estimating the publication date of this edition as having been anywhere from 1950 to 1955.
Mills passed away in 1972.