The screw holes you can see are from the small aluminium brackets that were put on by a previous owner, I removed them for the photos taken (have some before and after) someone has stuck insulation to the ceiling so I think when they have done this (maybe a backyard job) they couldnt workout how to utilise the headlining bracket so they have removed it altogether and made up their own brackets to attach the insulation and black velvet. From memory there was about 6-8 of these brackets with 2 screw holes in each of them and they are the screw holes you can see in the photos.