This brings up a good point on the Austrailian owned D.XII 2600/18. Often the refinishing or rebuilding by restoration crews tend to add solid colours to interiors for varous reasons.
Eight years ago I spent an entire day photographing and measuring that aircraft and the AWM's Albatros D.Va
I was given a research assistant by the AWM's PR
manager (actually, about 5 different ones over 2 days there and at Treloar) and allowed to take some considerable liberties.
One was to climb on a ladder and photograph behind the seat. The curator had been kind enough to expose the areas left conserved but unrestored
so that I could see the original interior colour.
We discussed it at length, including why
the AWM has a policy of "No fake histories" and the research that was being conducted prior to the imminent restoration of both of these aircraft. About things like spectrographs and stripping paint in layers a couple of microns thick to determine the painting history...
The interior was painted light grey. It was painted light grey at the factory.
Of course, he may have been wrong, but it sure sounded convincing to me. But then, like the AWM people, I am but a simple yokel