It's rail pretty similar to this one - it's the top left cylinder bar that's come loose/out. The cyclinder part stays on the outside of the wall, with a smaller pointed insert going into the wall to hold it in place.
http://www.comparestoreprices.co.uk/images/ch/chrome-heated-towel-rail.jpg...
We have a heated towel rail/radiator in our bathroom. Wonderfully, my old man managed to pull a part of it from the wall when visiting over the weekend.
The part that has come away from the wall is at the top, and is not connected to the pipes - it's merely a support piece that holds the rail...