First, let's remember that they didn't have telephoto lenses in those days, so the camera lens was probably very similar even if taken with different equipment at a different time.
Second, The picture of the "12th" has a irregular shaped bunker with tounge in the middle. In contrast, the "18th" photo has a kidney shaped bunker. The only way to explain this away, is that the kidney shaped green on the "18th" photo is off-camera on the photo of the "12th", and the same thing for the bunker in the "12th" photo - the "18th" bunker is cut off from the left hand side of the photo or obscured by the mounding on the upper left of the "12th" photo.
Also, despite the different angles on which the photos were taken, the distance between the bunker and the narrow green entrance is very tight on the "12th" photo. Although difficult to see on the 18th photo due to the angle, it appears much wider on the "18th".
Also, doesn't the depth and width of the "12th" green look substantially greater than on the photo of the "18th?" To my eye, the "18th" photo looks significantly smaller. Maybe that is just the lens compressing the depth, but using the people as a measuring stick of 6', the "18th" green looks thinner.
Also, I don't see a way for the obvious bunker on the back of the "18th" not being visible, despite the angle change, from being visible in the "12th". Although David's lime green circle around the white thing gives one pause. The front edge of the back bunker cuts the gentleman circled by David in blue at his waist. How could we not see that same bunker on the "12th" photo? Or do we? In Neil's photo, does the back bunker appear about waist-high of the man furthest up the hill? To me, the large face of the back bunker on the "18th" cannot be explained away in the "12th" photo.
Who votes to play the old green over the new one? I love them big and crazy.
Lastly, did Hawtree/Dawson also have a go at these to make them more pinable for an Open?