Corrugated iron covers on towpath bridge parapets

In and around Birmingham I've noticed several instances where a towpath bridge over a side arm has one of its parapets clad in corrugated iron sheeting.

This is on the Birmingham and Fazeley Canal near Cuckoo Wharf.

I guess that the modification is to make it more difficult to climb on, thus protecting neighbouring properties from trespass. It's a shame that a historic structure has to be defiled like this.