This is am ENEVER Tonneau Cover Bag is supposed to be a replica of the one made specially for Syd Enever. I suppose that means there was only one original, which also means it was not a period accessory (although there may well have been a similar bag offered for sale by someone else back in the day). This comes with instructions on how to fold the tonneau cover.

Suitable for short tonneau only, offered by the MGA Register for £16.50 plus carriage (shipping charge).