It hangs side-on to the exhaust and most of the attachment points along the length of the car - diff engine or gearbox - are straight-on, and so it wouldn't fit to the exhaust without a right-angled twist. There's no lower hole to clamp any other side to, to make a complete clamp, and in any case I've never seen any other part that clamps to it. It fits the profile of the Herald pipe but with nothing to clamp it, it surely must make a rattle as the car drives?
Here's the other one in better condition: