I saw an episode of National Geographic’s Wild Things on the big cats of England. They found some tracker/trapper dude from Canada who is meant to be a real badass at tracking/trapping cats of all types. They bring him to Britain and he goes about trying to find ANY evidence of their existance whatsoever.
In addition to being unable to track or trap one, he meets up with several of the leading “experts” or “researchers” and basically debunks every single piece of evidence they have. For example, the countless sheep/cow mutilation pictures clearly indicate something other than a cat attack. We learn that cats don’t tear and rip flesh in that way, but rather puncture when they bite down on a neck. Many of the tracks or footprints he finds that look promising are determined to also be non-feline due to aspects of the claw and pad structure.
This guy is no scientist, but he clearly knows his business. At the end he, of course, notes that just because they didn’t find anything doesn’t mean they don’t exist. But aside from eyewitness sightings of people swearing that they’ve clearly seen a large black cat, there’s no physical evidence to be had and most of the stuff touted as “evidence” is misinformed or misinterpreted.
Granted it’s just TV, albeit non-fiction. Sorry for the antecdotal summary, I’m unable to find a link to the show details itself. However, if you have the National Geographic channel it seems you can catch it again on Monday July 24th. It can also be had from various BitTorrent sources.