the geyish khaki should be fine, since wool is complicated to dye in a strong colour - the dye acceptance depends of the degree of degreasing, and then you have to regrease it otherwise it looses the weatherproof quality
so basically, through all times, cheap wool greatcoats have a lighter colour and look greyish brownish like the natural wool colour
or they are dyed with much surplus and loose the strong colour tone very fast