Well, it seems we can grow broccoli in Perth! At least in the winter months. I last tried around spring last year and the white cabbage moth was everywhere. I had experimented using moth shaped white plastic decoys, but I'm not convinced they worked.
We planted some dwarf broccoli in a small bed which gets a lot of sun throughout the day and we've had success! The magpies and crows thought they were pretty nice too - so we draped a bit of bird netting over the broccoli to protect the small heads.
We didn't get too many slugs or snails either - in general, all quiet on the bug front!
I'll be monitoring the change in seasons more closely in future, to really capitalise on the relatively mild winter and the absence of the cabbage moth more so!