Sometimes, research leads to unexpected results. This was the case while trying to find some more photographic evidence for the use of the “Helmet, Cork, Aviation”. Peter Suciu has already written about the two different types of this interwar period Royal Air Force equipment (here) but obviously the helmet was not only used by His Majesty´s Forces but was also popular with civilian users.
Even a book on a civil expedition can be a source for military pith helmets. (Author´s collection)