The building is located on the deal side of the golf club yes.
I was up there again yesterday so I took the camera and got a few snaps. On closer inspection it looks like a very small house with a back garden wall. However like I said in OP I can't see a reason why it would just be left unless there is some reason why it can't be removed.
Here are the pictures.




As you can see it looks like one room with a door leading out the back. Behind is a wall which looks like a garden wall. Also what looks like a broken chimney inside.
The road sign opposite to give you an idea where it is.

Dan