In Sep-2019 I shared a meal with cyclists near Central Market. Our bikes were parked in a side street off Gouger St.
A warning that previously someone had their bike light stolen. That evening one of our group also had a light stolen. I had a spare light, so rode with him to the Adelaide Railway Station where he caught a train.
I did not ask for the light details – attachment type, brand, value, battery size and type.
For emergencies I carry a back-up light – small, incorporates an attachment strap, labelled ‘Carbon Neutral Adelaide’, and compliments of ACC at a Ride2Work breakfast.
I'm sorry that happened to you. I always take my lights with me when parking away from home, even in the secure bike shed at my work. They are just too easy for someone else to remove.
I agree about always removing my lights, which I did religiously for the last 3 years until I forgot once as I stepped into a shop for 1 min.