Please could you send images of trim panels which could add to this post as examples which are original or you know have been copied directly from the original.
Rear panels round hood frame and back of cockpit:
Here are some from Chris Gould:
The Nippy trim panels were copied from what I think were originals except for the door panels. The “originals” were on my car and they had been recovered over the original trim. They had wood worm and I stupidly threw them away after copying. I saved some of the original covering, but over the years that seems to have got lost too. The boot side panels are cut away as shown. This is to allow them to bend round the wheel arch. Horse hair packing went between the arch and panel to give a smooth shape. I believe that the vertical “U” shaped metal pieces were folded over a strip of plywood to tack the panels to. The panel bottom edge and back edge were located with wooden strips.