Hm, well it didn’t appear in “AlaCarte”, but on 2nd thought I re-ran the application, and using the string I could see b4 being cut-off ran a grep search:
share/xgreeters/slick-greeter.desktop :2 :Name=Slick Greeter
share/xgreeters/slick-greeter.desktop :3 :Comment=Slick Greeter
share/polkit-1/actions/org.x.lightdm-settings.policy:12: <message>Please enter your password to configure the slick greeter</message>
So mystery solved, I had installed Budgie (since removed). Must be a artifact of that install? I didn’t install lightdm on my own.
Thanks for all the helpful responses, people!