Being from approx in the vicinity of the other side of the world from Vegemite-land I came across it at a mature age ( mid 1960's ) thanks to the antics of Barry MacKenzie. Has it ( like almost everything has ) been reduced in quality since then ?
......IIRC Marmite was linked in some way to the production of Guiness back then. Now its just something in a jar that Unilever ( or some such ) churn out / discontinue as the humout takes them,