Went for a walk in the local woods, and found a branch that had come half way down before resting on another tree. I managed to pull the branch down completely, and this was the other tree after - it's amazing the damage the rubbing of one branch against another does. It was making a small squeaking noise as it rubbed.
Check out the extras for a tree arch I found nearby. (Excuse bad focus on extra, still getting used to new camera!)