Airframe Internal Metal Colour
or at least undercarriage doors. We had a bunch of guys up here at Manchester from AF at Filton last week. They needed a "Concorde fix". While underneath on of them said "Oh Yes your doors are different colours like ours."
I'd never noticed that the metal on the inside of the main undercarriage doors that are open when she's on the ground are different colours. One is a drab green and the other is khaki.
Is there any reason for this or is it just a new one has been fitted at some time and happens to be different ?