We are ‘scribblers’ from Australia.
In terms of personal history, Arthur spent just over 20 years in the Australian Army Infantry Corps from 1963 to 1984 (serving 2 tours in Vietnam).
Mark spent 5 years in the Australian Army Medical 
Corps from 1984 to 1989 (serving with Reserve/Regular/Integrated Units).
We both put together very small military insignia collections, based on service background (Arthur: in Vietnam campaign areas of interest and Mark: on Commonwealth Army Medical Corps insignia and ultimately Medical Corps from all armies).
So, we are ordinary everyday militaria collectors who decided to write a series of guide books for other collectors, based on our personal familiarity with the Australian Army’s customs of service.
Here is a link to a brief introduction to the work and places where the hard copy and the electronic edition can be purchased:
Amazon, eBay and Gumroad etc
charliebravobooks 