Just a thought but I guess SYD-LHR or LHR-SYD might be a "holy grail" if destinations with a common language ( on second thoughts) is a driver....
OTOH if people travelling on a non-stopper then connect into/out of LHR for mainland Europe in significant numbers ( and they certainly do on the current direct services...) then maybe FRA -SYD would make more sense to target as a non-stopper.