One of my guests at the moment is a Brit/Aussie and travels annually to UK, he resides in SYD, when I mentioned to him about the PER/LHR service at first he joked about the Western Australians not being sufficient to justify the service but once he gave it some thought he commented that there are a lot of poms living in the outlying regions of WA.
But when I pointed out to him that en-route stops in the likes of DXB, BKK & SIN are wasted time but during a stop in PER one could clear customs & immigration and arrive in SYD as a domestic passenger his face lit up, he liked that idea.