I don't think they were stained. My first TR, a 1967 - TR4A, had an English Walnut (veneer) facia. As the finish aged the varnish became brittle and cracked. I carefully removed all of the old varnish (it wasn't transparent - sort of looked like orange shellac). The resulting exposed veneer was fairly light for walnut, so if a stain was used it must have been neutral, perhaps for sealing purposes only. We refinished the facia with a Danish oil treatment which resulted in a deep satin finish - beautiful. This was my preference. But, if I had used a high-gloss exterior polyurethane varnish,I believe it would have looked very original. Alas - no photos survive.