Spookily I saw some yesterday on a verge of a nearby dual carriageway. I remember one solitary plant in a field where we walked our dog when I was a child which was why the little clump on the roadside caught my attention. Just a little further on were some Southern marsh orchids.
Orange hawkweed, or Pilosella aurantiaca, will take over completely if left alone. It's great for insects, and particularly pollinators, but it is invasive so you need to catch it quick unless you want a field of them