Originally Posted by libertyuk

I'd agree, if you don't want to overnight, I'd do Qantas A380 all the way (it's via SIN), you're Silver so you get lounge access and you might just have enough time to shower at SIN before reboarding, otherwise BA A380 to SIN, then change ont the 777 to SYD, plenty of time to freshen up at the BA or QF lounge at SIN. Overnighting makes a difference, but bear in mind the BA and QF options via SIN are all overnight and all arrive in the morning in SYD, which makes it tricky to get a hotel room for early check in (unless you pay). Overnighting at HKG is better, as you can go BA to HKG on A380, then overnight at a hotel near the airport, then get the daytime CX flight to SYD (but I'd check if the 77W on that is now a 10 abreast one, which you should avoid).

The other option often ignored is JAL via Tokyo, JAL on a 787 (LHR-HND) is the most spacious economy class of any, with more seat pitch and the original 2-4-2 seat arrangement 787s were designed for (not the 3-3-3 all other airlines use), but then you have to change airports to NRT (but could overnight in Tokyo) to go JAL to SYD. Take your own entertainment, eat before the flights if you are not into Japanese options, but for seat comfort it is hard to beat.