Okay, so I think it might be from the Lygaeidae family. Some info is here on the CSIRO website. It says they're a large family and include lots of agricultural pests (which must be why I was vaguely familiar with them).
They're also called cinch bugs.
There's another good website here from CSIRO again, but not much on my bug.
Oh, well, not a lot of info but at least I'm back taking photos of critters (even when my ID is wrong!) :)