WH Smiths used to sell chinagraphs. I used them as lot as a driving
instructor - had diagrams in plastic display book and scribbled all over
them as needed.
Just don't leave them in the sun inside the car or the insides all run out.

--
Skipweasel
Pay no attention to that man behind the curtain.

Funnily enough I went to WH Smiths, couldn't find chinagraphs, nor
crayons, but did find a semi-permanent liquid chalk pen!