Since when do Australian cities have flags?

Outside of the Olympics or the driveway to the United Nations, how often do you think about flags? Countries and states have them but Australian cities have them as well. And unsurprisingly for something that was created largely during colonial times, nowadays these flags can feel a little problematic. So what's the history behind our city flags? And is it about time we gave their tired old designs a bit of a refresh?Guest: Nick Baker for ABC Digital