It's hard to imagine any other situation that would lead someone to paint over the reflector...Apart from a desire to carry out a nocturnal suicide by motorcycle accident...:laughing: ....Ian
I think so too. Many of the 8" headlamps pre-dated proper masks and if the painted out or backed by a paper mask Difusa lens became broken then the vehicle was left with as brightly silvered disc at the front...I can imagine that they may have wanted to tone it down.
The black area is odd as it seems to have been applied later and doesn't really seem to comply with the instructions relating to blacking out half of the reflector when used with the manilla mask.
It's impossible to know for certain when it was done of course but there are plenty of images of the semi-circle cutout paper masks fitted upside down (or half rotated). I wouldn't rule out either that someone had fitted the reflector upside down before painting it.
Painting half the reflector black was a government decree early in WW2, I have a bicycle light painted like that, as the war went on the rules got even stricter, so I suspect this is probably original.