Any time, especially with film, and more especially with older generations of color film from around that time period you take pictures in anything other than natural sunlight your colors are going to be off some way. Every type of indoor lighting has some sort of tint to it, florescent has a very green tint, tungston has a very yellow/orange color. Flash corrects this color shif to some extent, but the flash falls off or doesn't cover the whole photo completely. To make matters worse you have the printing process to contend with, the printer may have tried to compensate for this and altered the colors further. Unless the person printing knew EXACTLY what the original was supposed to look like, the color isn't going to be perfectly accurate.
On top of all this, take a look at your own family photos from that era, the color has shifted from when it was originally printed. I would assume the same thing probably happened with these original prints.
Digital enhancements definately help to get back to the original color, but it'll never be perfect, especially in the case of this helmet that we don't know the location of today so we can't verify it.
