Took climbing friends who were visiting from abroad to a crag on Portland, Dorset. As it was a new area for them, they set up an abseil line, (threaded through the staples) on a neighbouring climb to take some photos. Once they had finished, I then got on the fixed line from above to take some shots of them. When abseiling down, I got to the bottom and the rope whipped through my belay device. There was no knot tied into the end and if any higher up I would have dropped off the end of the rope.