Something fishy going on

We've walked past this drain a couple of times with the dog, but today it was light enough to take a picture. There are actually three of these fish mouth drains on the house, two on one side and one another. They are rather ornate and unlike most French down pipes which seems to be a patchwork of dented and battered chaos these are rather grand.

In the UK down pipes used to be made of cast iron, so until they rusted away there nothing happened to then, Now they are usually made of a plastic, and unless you hit them hard enough to break them, nothing happens to them. French down pipes are mostly made of zinc or galvanised steel (not sure), which is softer than cast iron and unlike plastic which springs when up bump into to it, zinc bends and deforms. Pretty much everywhere you look the down pipes are bent or dented somewhere...!