If it were a Cormorant instead of a Heron I might agree with you Andrew. I like both the Heron and the kingfisher but I hate the Black Death (cormorants) when they start to spread in land.
No enemy at all! The heron is a natural inland predator same as grebes and kingfishers. We used to have one by our weir, but I had an eel pass installed in October and I don't think he appreciates it getting in his way.