When I typed "Caldron Snout" I hadn't thought I'd misspelled it. Most references spell it "Cauldron" I now see, though Britannica and my seventh series one-inch OS map have it as "Caldron." As ever, I think I'm right and that everyone else is wrong! ;-)

Whatever. Cow Green reservoir, which stopped the Upper Tees from flowing free forever, was constructed when I was a botany student at Imperial College. It was regarded as a tragedy and an outrage by anyone remotely interested in conservation, but we lost, as the judge at the appeal chose "people over wild flowers" (as he put it, I recall). The reservoir flooded large tracts of some of the rarest and most beautiful wildflower habitat in Britain, and its dam regulates the flow at Ca(u)ldron Snout and High Force, to compound the outrage.