I don't think these chairs had been abandoned but were there for some other purpose as the woodland in question is actively coppiced. https://en.wikipedia.org/wiki/Coppicing - crop from 6x7cm negative
This is the universal chair, in use around the world..!
I used to live near a private school abutting a river. Canoeing, I discovered the place's janitors had a fishing setup with same, smaller scale. It looked like a peaceful small world.