Bedford used a black primer , I found it on most of my Bedford , mudguards and bonnet included. over it was this early british olive drab , inside the dash it was well preserved , over it was another coat olive drab , and than a rather greenish paint finish with no markings and finally a coat white , and red as final coat .
This black primer is far superior to the olive drab they used , so maybe it came off during the years , on my chassis under the body there were only few spots were the olive drab was still attached.