A lot of railway structures are not listed. Bridges are particularly threatened at the moment as they are not high enough to allow electrification. This is shame considering how historically significant these railways are. Network Rail are very relaxed about demolishing Brunel structures.
This is one thing I just do not understand about many of my countrymen. So often I seem to read about wanton destruction of precious places such as buildings, forest and so on. Some of the destroyers are demonstrably ignorant/moronic, but the worst are the intelligent but sociopathic cynics that wilfully destroy, almost always in the hunt for profit. Ugh. For example a property owner near me destroyed some greatly loved ancient woodland in defiance of legal protections on the woodland. His response to legal action is to sell the woodland - if there were any justice he would be forced to reforest it, and fined half his fortune or something equally fierce. We don't deserve to have nice things around when we let these people thrive.