Being a total Western nut, I think that I have bought nearly every book on Westerns that was ever written. Needless to say, lots of pictures crop up in more than one book. Its most certainly true that photos that look like (so called)Chromatic Blue in one book, look totally different in others. I remember that when the best we had was Fuji and Agfa film, one of them totally exagerated blues and greens and the other did the same with Reds and oranges. Not sure that the printing was very good in the 60s and 70s either! I'm fairly certain that Swindon mixed some odd brews of Rail Blue to start with, before BR HQ got them under control with a more precise paint spec. On the Cover of Adrian Curtis's book "Westerns: Volume One - Swindon Built Locos" there is a great picture of 17 and 37 in BSYP, next to a 600 (Presumably D602 - Bulldog) which all look very chromatic. However, a later picture of Warrior in the same livery on Page 77 of the same book, looks very different. Similarly, a picture of D602 "Bulldog" taken soon after at Plymouth on Page 10 of Strathwood's "Warships" looks almost grey!