Originally Posted by louie-m

You might want to give some thought to trying to use the Avios multi-carrier chart - https://www.britishairways.com/trave...e/public/en_gb. Either for the whole trip, saving the 2-4-1 for another trip, or just for the non-LHR flights in addition to the 2-4-1. Business is twice the Avios shown on the chart, but from reading on FT it seems if your longest flight is in economy, the whole trip would be charged the economy price. So a significant saving if you could put up with either SIN-LHR or SYD-DPS in economy.

That said, finding availability would be difficult to put it mildly, you'd probably have to bend your itinerary to fit in with OneWorld routes and taxes would probably be eye-watering. But still worth considering. Maybe best to grab the LHR flights with the 2-4-1 first if you are considering this to give you certainty, then cancelling that later if you can make something work that doesn't include those flights.

That said, there are a lot of low cost carriers in Asia. Fewer in Australia!

Good luck.