Restored windmill
I've attempted the restoration.
Here is my reasoning.
1. Agfa and Kodak both had a color print material in the 40s if not earlier. We do not know when the original photo was made nor with what, but color films existed in 1937. Those films had a bad cyan dye fade problem and an orange dmin problem in image areas as the print or slide aged.
2. Restoration via PS recreated an image that appears to be a fall scene with normal(ish) flesh tones and the man is wearing a red shirt. The highlights show some of the orange dmin. But, the sky is reasonably blue. The whites retain their whiteness but highlights with dye have turned orange.
3. With restoration, you can see some green in the hedges and tree highlights.
So, I see several colors including Blue, Orange, Red, Green and Flesh. I discount any pigment process due to the good stability, but then this might be a rather poor example of someone's printing technique. IDK. The print original sample is suggestive of a 2 color or 3 color reproduction process with severe image degradation.
Without definitive proof, any of us can be right or wrong. I submit this to you as an example only and remind you that PS has a mind of its own, often supplying things that simply are not there.
If it is there though, I feel fully justified in my conclusions based on what I see. OTOH, you may be wishing to see the sample just to jump all over me. If so, have fun. It is not that big of an issue due to the digital transformations, lack of information and severe aging. The original size and the resultant digital artifacts have not helped this issue.
I doubt if it was hand colored, as these would have probably been pigments.
I have tried to give the best estimate that I can of what this original might be.
PE