I think I can see how it works .........................

Looking at the Heiwa Japan site earlier I happened upon a set of pictures of a Matchless G3 they are building up over there at the moment. One of the shots showed this pretty fancy seat mounting arrangement, took a bit of time to figure out what's going on here. I think the idea is for the seat pan to remain flat through the travel and not pivot around the nose bolt as is common practice.
Pretty trick answer to a problem that doesn't exist if you ask me, but innovation is the name of the game so all power to 'em.