have you looked at Philippine airlines? they currently have a return business class special from Brisbane to Manilla which is not much more than economy and then you could get onward flight to LON. Best to ring the airlines and ask them.Staff are very helpful. Phone number on their web page.

Also look at Qatar although not sure if they leave from BNE. What about EVA airlines ? China Air based in Taipei is also supposed to be good. Good luck.