It's not the worlds longest flight, Dubai to Panama City come in at around 19 hours, but it's certainly up there. I'm not sure if there is enough demand from a Perth size city for a non stop London flight as people using it would be primarily going to London only, with Singapore or the Middle East offering better connections.
I certainly wouldn't want to spend 18 hours non stop in a 787 with 9 across seating, just thinking about it makes me cringe.
