Some years ago we were bought a hedgehog that had it's head trapped in the handle of a plastic bag. It took us some time to release it and once it was we found the plastic had cut into the neck, from ear to ear. After treatment the hedgehog made a full recovery but it was something that could have been avoided if the bag had not been dropped in the first place.
Heartless or thoughtless people sometimes subject hedgehogs to deliberate cruelty. This is now illegal. Should you see this occurring, contact the Police or R.S.P.C.A. If the unfortunate hedgehog is injured, try to get it to a veterinary surgeon as soon as possible. In any case, please let the British Hedgehog Preservation Society know about it.