Thanks for your advice fellas. Will have a go with the graphite although the soot from the coal fire sounds interesting, once on v hard to get off. My lounge carpet will testify to that! The graphite trick sounds like the one outlined in the article mentioned in my first post.
Do you finish the surface with 2 coats of 50/50 thinned matt Ronseal varnish & water? I used that on my Basic 3D and the covering has stayed v clean even after 18 monthe of regular flying with no pealing of stickers.
BTW stuffed the Superair today so that' now on the repair bench!