Western Australia doesn’t appear in the preamble to the Constitution Act:.
.....WHEREAS the people of New South Wales, Victoria, South Australia, Queensland, and Tasmania, humbly relying on the blessing of Almighty God, have agreed to unite in one indissoluble Federal Commonwealth.....
Maybe that’s why it’s Govt is so recalcitrant on the border issue and the ongoing secessionist ideas that bubble along within the State.