Want to remove black plastic panel behind rear number plate on 1990 4x4 Cosworth. Searching on here suggested a nut on each corner removed from inside the boot. What I have in each corner looks like a captured fastener (seems to be made of rubber) that looks like the screw needs to be undone from the outside. One of them almost seemed to let you just push the threads out through the rubber but others not so easily. I have hopefully put a picture of the inside of the boot but not sure if I have done it right. Thanks David.