If it's bayonet in my understanding of the word, and it certainly looks like it is, since the picture plainly shows the J-hook.
The blue goes to the terminal that connects to the shell of the socket, i.e. The part with the little slots in it. The brown goes to the nub in the middle. This choice makes you less likely to be shocked while changing a bulb.
Blue is neutral and is designed to have a voltage near earth.
Cheapie LEDs often do a shoddy job of insulating the exposed parts. But just the same, the engineers try to make it so if it fails, it fails with exposed parts faulting to the shell. If you wire the socket correctly, this improves safety.
In UK wiring, it doesn't matter which wire goes where in that particular B22 bayonet fitting. I'm guessing the same is most likely true in Australia too.
Here's an equivalent fitting for a typical pendant lampholder - you can see it is completely symmetrical.
Even with the type of lampholder with metal conductive bodies, there is no connection between either of the pins and the shell. The shell has a separate ground connection.
Again the notional live and neutral elements are completetly symmetric - it doesn't matter which one is connected to live and which to neutral
In fittings where it does matter, Live and Neutral will be clearly marked. For example with "L", "N" and "⏚" or "E".