Who was the first Australian to invent a tank?

Australia purchased Centurion tanks from Britain. The primary way to tell the difference between the two, is the Australian crewmen had removed their armored side skirts from their Centurions in Vietnam, so as to prevent the build-up of mud/debris during movement. Secondly, all Australian Centurions in Vietnam had a external 100 gallon fuel tank attached to the tank's stern section.