Because I am a 'must know' sort of person, I contacted the Museum of Victoria. The Museum's "Discovery Centre" replied the next day.
Apparently there are two similar species. Prietocella barbara (previously known as Cochlicella barbara) and Cochlicella acuta. Both species are migrants from the Mediterranean and deemed to be agricultural pests in Australia!
The Museum thinks this one is probably Prietocella barbara because of my location.
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Since this 'photo opportunity' the little snail seems to have disappeared.