UPDATE: Geometridae/Ennominae (Fisera perplexata - winter form)
The moth is about 3.5cm in length.
This shot was taken when said moth landed on my back door and it's not very clear, but it shows the stout body. The hindwing was grey.
I may be forced to annoy the Museum of Victoria again with yet another query!
However, if there is somebody who is able to correctly identify this moth, I would be very grateful.
*I can hear you laughing from here, Duncan! :)