What is odd flying from the UK to Australia, is that you often have more choice of long haul flights with the Mid East 3 + SQ than say Qantas. We go to Adelaide a lot and it's served by Emirates, Qatar, SQ (and Malaysian) but not BA or Qantas long haul. Similar in Brisbane. Also gives you a lot more flexibility to go in at one airport (eg MEL) and out elsewhere (say ADL).
We've also found that sometimes you get MUCH lower fares, especially in Business. if you fly via AMS or CDG - which isn't a hardship if you're not in London already