I'm quite aware of the wide grayscale variation in negative based film/prints. There simply are too many variables in film type used, camera and settings used, filters that may be applied to the camera, the weather conditions, where the sun is or existence of cloud shading, plus the whole print processing introduces potential variations in shades seen to know what is the color by grayscale shade. It is really impossible to determine specific "colors" from B&W film without additional information. Knowledgable people familiar with the ship and what paints were being used in the time frame of a given photo can give an educated estimate. I scanned this image myself at US National Archives (NARA) from a print in a collection called the 80-G collection of mostly USN taken views in grayscale. When I scan I do NOT change the settings to make the image lighter or darker ... it is what it is. In general the scans look like the prints, except that aging sepia tone of the print paper isn't seen in the grayscale scan.
Having said that, it is normally difficult to produce an image like this one if the subject ship was painted in a dark gray. If this paint has a blue paint component to it, then it will naturally show up lighter with many films of the era. Here are samples of some of the other images I have scanned from another collection of prints at NARA called 19-LCM that date in the 1940-41 early war period. Whether all those dates provided on the prints are accurate, I can't say. It should be noted that it appears to me that many of these photos were provided to the USN by the RN during WWII for recognition purposes. Also, many (if not all) were prints made from copy negatives. Copy negatives have a tendency to increase contrast.
Two images of HMS VIMIEA supposedly taken at the same time in 1940. One is darker (and further away) than the other image. The darker shade than the other image is likely due to backlit sun on the subject.
HMS FERRIE dated 1940. She is a lighter shade than most of the others here.
The next three images are all in a darker shade, which I would assume shows Dark Gray 507A
HMS GARTH dated 1941
HMS IMPULSIVE dated 1941
HMS JACKAL dated 1941
Then we have.
HMS KIPLING dated in 1940. If reports are correct, she was one of the destroyers painted in Mountbatten Pink.
So for the image of HMS MATABELE, the only difference with this photo from the others above is that it is an aerial view and the details are sharper than many of the above images. The black and white (or light gray) on the mast would seem to put the paint on the ship somewhere in between and fairly light in shade.
So I taken it that this photo dates HMS MATABELE to about a one year period from when the 2nd TRIBAL Flotilla became the 6th Flotilla in April 1939 to May 1940. So, it could have been taken early in her career before the war started.