Strongly recommended NOT to fly BA to Australia, especially in economy as you will NOT be fed for about 8hrs after the main meal (unless you go into the galley where you are offered some smarties from the tuck box!) and when you do get breakfast it's pretty pathetic (actually, it's outrageous!) for such a long flight!
At the moment I choose Singapore and JAL to SYD (drinks and food on tap!), but am hoping VS will provide a decent service on the LHR-HKG-SYD route!