Thanks for the replies, useful info.
While we're at it, does anyone know if the secondary Class D (old GAAP) airports like Moorabbin, Archerfield, Parafield etc require the display of an ASIC. In the ERSA they are listed as "security controlled" aerodromes but I remember a number of years back even with that status, there was an exemption that no ASIC was required if you didn't go near RPT areas etc.