If it was Roman it probably would have been found in connection with a Roman settlement, along with other artifacts. Can I tentatively suggest that its 'purpose' would probably have related to either domestic use or if something 'religious', a statue of a god recognised in the local area/across the empire - what I'm trying to say is, the artfact probably wouldn't have been an isolated thing like the carving. The fact that it's 'abstract' and we can't really say what the hell it was / was for /represented - means that its context is so much more important. The siting of other examples of rock art is presumably thought to be important.. that's why to leave it in its setting seems more important. There's lots of rock art stuck out on the moors on huge outcrops of rock, we don't try to chisel that off and bring it to a museum.

..er (I'm trying to get at something it's just hard to get at it, bear with me) so I don't think it's 'anti-prehistory' or 'pro-Roman' to want to remove a Roman artifact and leave a prehistoric one. Maybe it's partly to do with notions of 'civilisation'?

I don't know. I'm sure there's something wrong with your suggestion though (with the greatest possible respect)?

Also this stuff about the rock art deteriorating if it's left where it is.. it's under the peat where it's been for years - will it start altering now? What type of rock is it? It'll be pretty acidic under there. That's what makes me think that any chemical reactions with the rock that are going to happen will have happened long ago. It's either something tough that doesn't care, or it'd have been dissolved before. Just an idea.