I was just about to say that it sounds like a typo because I couldn't find any mention of anyone called Degil when I stumbled across a couple of books illustrated by Degil. It's a very, very uncommon surname: I've found one reference to an Adile Degil in the 1861 UK census and a handful of Degils in the USA. The name appears to be of French origin. Otherwise, nothing. I can't even find anyone of that surname in the phonebook. Frankly, I'm stumped.
The House in the Holly Bush by Josephine Hatcher. London, Burke Publishing Co., 1960.
The Gasworks Alley Gang Goes West by Josephine Hatcher. London, Burke Publishing Co., 1961.