Ok, think I may have found the issue, I pulled the plastic on the back of the boot and it moved very easily. I think this is what it is.
I have taken a pic to
help me explain what I think it is. Basically there seems to be some metal clips that hold onto the plastic trim and then stick in a few holes on the metal of the boot and they seem to be stuck in the metal part of the boot:
This picture is looking through the left hole in the boot where you can change the bulbs
This is the same on both sides. Could this be what it is? They definitely look like they should be stuck to the plastic trim as they have clips for them.