Just a brief thought… There is a little blurb that suggests a brief (and I don’t know how accurate) history of child detectives in the back pages of the Vintage Classics translation of Emil and the Detectives (2012, translation by Eileen Hall). There will be books on the subject, but still… under the title, ‘Child Power‘ the publishers include these words
“When Emil and the Detectives was published in Germany in 1929 Emil was one of the first child detectives to appear in a book. Emil and his friends are heroes, they stick together, they outwit the thief and accomplish something that even the policemen hadn’t been able to do. Today you can read all sorts of brilliant stories about clever child spies (The Famous Five, Anthony Horowitz’s Alex Rider books and Eoin Colfer’s Artemis Fowl) but little Emil Tischbein was the very first!
“The children’s author Philip Pullman loves this book because he says ‘it is a great political story: democracy in action’. And it is true, Emil and his friends are organised, they share their money, cooperate and they are extremely disciplined about a common cause – bringing a thief to justice.”
Add to that the fact that Kästner’s books were burned by the Nazi regime and I think it is an interesting analysis.
Ref: np. Author not named (emphases in bold highlight the critical focus I found interesting)
Emil and the detectives / Erich Kästner ; translated from the German by Eileen Hall ; illustrated by Walter Trier. Vintage Books London 2012