So, with 12 hours to kill on a quiet day at work, and all the toys of a £1M bodyshop at my disposal, here's how Olive Drab, FS 34087, would have officially looked when brand new. No doubt there would have been variations as mentioned earlier due to batches being made slightly differently, mixing in the field with whatever was available etc., but this is the "benchmark" shade as it were, 1942-1959, according to the information I have.
Wet paint in the pot in the middle, natural finish on the left, matt clearcoat on the right.
Pretty much a 50/50 mix of a yellow oxide colour and black, which would tie up with one story I heard that they just added black to primer to make a low visibility colour.
A completely meaningless excersise, but it passed some time for me today