Thanks Peter.
I have finally figured it out now.
So for any future reference for anyone with same lack of understanding:
The parcel shelf, as Peter described is a fibreglass formed shelf covered with a thin foam and then the black vinyl.
There are 2 captive (although not really as they are moving around underneath the vinyl) bolts facing down from underneath the shelf. These slot through the moulded fibreglass top cap of the back panel then the metal sheet inside the rear top of the boot.
The bolts are then accessed inside the boot at the underneath the metal bulkhead and then have nuts attached to hold the shelf in place.
The back panel referred to, is a separate piece and is also covered in vinyl and has the studs fixed to it for the tonneau cover press studs.
The back panel is fixed (not sure how yet) across the rear metal bulkhead behind the rear seat back rests.
As with a lot of these things it's all very fiddly getting the bolts back through the fibre glass cap and metal in the boot to then put the nuts on the bolts.