I would prefer going on the qantas flights anyway so hopefully they are at least accommodating enough to change the day, although I am biased by going via HKG for a couple of reasons firstly gets in to London at a nice time, chance of still only being sold as a three class flight so might get lucky and travel in a first class seat with Business service

so I will see what happens when I call qantas tomorrow and let you know how it all goes