Hello,
I'm not sure I would trust any early B&W photo for colour balance as they are taken with orthochromatic film. This film type did not display colours as they were. A classic example is the British Union flag.
Attachment:
Union%20Flag%20Orthochromatic.JPG
Union Flag Orthochromatic
Attachment:
Union%20Flag%20Panchromatic.JPG
Union Flag Panchromatic
Attachment:
Union%20Jack.gif
Union Flag Colour
The blue of the union flag is completely different between the orthochromatc, much lighter, and the panchromatic which is similar to the colour in tone. So perhaps the Admiralty Fleet Order of November 19, 1914 should be followed; Hulls and weather work of all H M ships in home waters except torpedo craft to become light grey. Mixture to be 1 part black to 20 parts white by weight. Yes it is called light grey, and it is compared to the grey of 1902, but is it still a rather dark grey. Using current paints and by volume rather than weight the ratio for this grey is 3 parts black to 4 parts white paint.
Orthochromatic film was also very sensitive to exposure resulting in too light or too dark if you got the F stop wrong or the time of exposure wrong.
Cheers,
George