There is certainly no doubt in my mind that the misformed rim on my damaged 8" lamp was original factory finish KG3. This would probably have been November 1939 production.
The mask inside my MT110 was of thin black card. I beleive that there are surviving examples of pre-cut headlamp masks in black card too.
It's difficult to be sure of the card colour in all headlamps, but it is the case that even with black card, reflection on the exterior of a 'Difusa' glass often gives a light colour in a black & white photo.
Thankfully, none of this is relevant to BEF as they painted the glass.:grinning:
Definitely looks like khaki green to me in these late 1939 - early 1940 photographs with brand new Triumph SW3s.
The SW5 may already have had a (black) blackout mask. These are later SW3s, more or less from the same period as the SW5.
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I suspect that the two images with black-painted blackout masks show the bikes after retro-fitting.
This is a C7828 5SW (the contract was delivered late June - October 1940).
Clearly "Service Colour" (i.e. KG No.3 at that time) on the complete headlamp assembly.