Postal history research is a form of detective work. Sometimes the social environment is more interesting than the postal history.
On this Hungarian first inflation registered cover, the sender’s coat of arms really stands out. If you look closely, you can see the Order of the Golden Fleece. There were 31 Hungarian members of the order, and the only one still alive was László Batthyány-Strattmann, the “doctor of the poor”.
(I’m not a coat of arms expert, so if I’m wrong, please write me the right answer.)