"I suspect that the incident at Appleby was not isolated, as someone has pointed out, the number of witnesses with modern devices such has digital cameras, mobile phones with cameras etc...makes this particular incident high profile"

...and the 20 - 30,000 visitors (as estimated elsewhere on this thread) who visit the fair each year would no doubt have similarly recorded any other instances of an animal being drowned in the past. If you have evidence to contradict the notion that this particular incident was a one-off, do please produce it.