I am trying to narrow down when they were taken. Apparently, they were off 2 weeks ago, but I didn't see anything said about it. We'll see.
History - No Idea. A lot of people think it's a coal wagon. I haven't been exploring long enough to know about the removal of the tub from the gas chamber (which in and of itself, is just fine, it's just the manway top-right of the chamber that needs to be avoided). The survival of working winches in there is nice, and I would not want to see them disappear.
I can't see any other reason for them being nicked other than someone into railways, or on their behalf. There is a lot of cross-over with mine exploring and Railways with a lot of blokes being into both, so if someone goes around offering these, we may get to hear about it.