As a matter of interpretation, the Constitution has to be read in light of the later, constitutional enactments. The Constitution in 1901 is different in nature to the Constitution today: it was an act of the imperial parliament at Westminster. Since the Statute of Westminster and the Australia Acts, there is now a separate crown in right of Australia, and the notion that this change has somehow not affected the Constitution, seems a novel one. Skyring aka Pete's analysis above, while interesting, is original research based on his or her reading of the Constitutional text itself. No one, not even the qualified lawyers amongst us, is entitled to present his or her original research as fact here, and to suggest that it is the monarch in right of the United Kingdom who sits at the apex of the Australian legislative system today is inconsistent with all of the heavily cited articles we already have - e.g. in Monarch of Australia. 

 If Skyring wishes for his or her novel, originalist interpretation to prevail here, he or she will have to convince the constitutional law community in Australia first that they have been reading the Statute of Westminster wrong all these years!