The boot lid assembled. There are three main components - a lid with framework welded to it; a thick ply baseboard and a steel tray. There are also wood fillets at the top and bottom of the lid, and the lid is completed by a wooden strap strip and a rubber mat.
Three long screws (centre rear) pass through the tray/baseboard assembly and fix into a strip of wood the length of the lid. This strip is secured to the lid by the screws holding the locks
The four side screws only hold the rubber mat to the baseboard. The sound deadening is non-original.
With the inner tray/baseboard assembly out, the lid can be seen to be an outer skin, welded to a steel angle iron framework.
The piece of wood at the bottom is probably the remains of a larger piece that the tray/baseboard assembly had been screwed into
and the angle iron continues around the lower edges of the lid to form a rectangular holder for the tray/baseboard assembly.
The tray/baseboard assembly comprises an outer steel framework, which is a snug fit into the holder above
Once the baseboard is in place in the tray, the rubber mat and wooden strap strip are screwed in from the top.