1920s Clothing (a few examples are from western countries other than Germany):
As well as visual references, I’ll be looking at the description of place within the book.
Neustadt (possibly Titisee-Neustadt in the Baden-Württemberg area of Germany. Grand Duke Charles of Baden would support this to be the case.)
*edit- according to the most recent publication of the book (a puffin book with facts etc.) the town is Neustadt an der Weinstraße in the state of Rhineland-Palatinate.*
1920s German Trains: