Is this outdoor light wiring correct?
Thanks to clues from folks in the comments I solved this by simply connecting the two dead ends together to form the switch loop. They had obviously come loose inside the lamp (possibly through wiggling of cable when lamp angle changed).

With these ends connected, the wall switch ON and power OFF I could confirm conductivity between the previously loose end and the live terminal on the lamp. This gave me the confidence that one of the cables indeed went to the switch and identified the live wire. (no useful colours to go by).

With power ON I could confirm 240V between the live wire and the neutral connection  on the lamp, and with the switch ON also I confirmed 240V flowing between the L+N terminals on the lamp and the bulb contacts.

Light now works. Thanks all commenters.