This is just something that I've been wondering about for a while but don't seem to be able to find an answer for.

On the ignition, next to where the key slots in, is a little button. What is that for?

All my searches that contain the words ignition and button just take me to push button starters.

Key in , press button on lock, turn key opposite direction to normal, remove key. Side lights now on with key removed.
For parking on unlit roads during darkness.

Nice one. I've jigged the key about before whilst pressing it but never turned it the opposite way. Cheers.