I'd say that is a trick of the light or they're in undercoat on a trial as they were turned out in '64
If you look at this B&W and put a sheet of paper over the lower part of the tanks you can convince yourself they're in ivory too
Sorry Noel, I started to watch the video , then posted, then read your post later but yes we're thinking along the same lines about the turntable here (if someone can verify, please)