Maybe luck, maybe my check-in agent wasn't on the ball or as helpful as she could have been (I was holding an I / Business class ticket, but didn't think that would have passed her notice), and maybe I could have tried with QF to see if they'd accommodate me.
To be frank, I'd had a bit of a rough night, and was in no mood for horse trading, so I didn't push it with anyone and just copped the delay.
We were re-scheduled to leave at 0930 and arrived just before 1100 SYD time (they'd advised us in the air that we'd make it by 1030, so something must have slowed us down unexpectedly in flight). It was a bit of a race through customs and on to the train (no messing about with the bus) and just managed to make it in time for my 1200 connection (separately ticketed, naturally - thankfully I had hand luggage only!).