You hear stories from time time to time, usually from people I know that hunt in out of the way places, but I have never seen one or traces of it. I think it's not improbable that there could be some out there in the wilds; there is enough game to feed them. If they lived right out in the country side then it's feasable for them to live for years without been seen, apart from the odd sighting but these are normally only for a short time & by time the viewer's brain has said 'Thats a big cat... Oh ****' then they are useually gone. Hence there are not a lot of photos.
I read a fair amount on it a few years back & then went to London Zoo a bit after that, where I spent some time looking at the Big Cats. There are quite a lot of them that are not really that big i.e. the same size as a medium to large dog. There are also some quite big domestic & feral cats about, especially the latter, which could quite easyly be confused with one of the smaller Big cat species. I once saw a large feral cat while out pigeoning on a local farm that was the size of a female labrador. Big but not huge & it was definatly a strain of domestic cat. It was after my pigeons in the decoy pattern but got wind of me and was off. Interesting to see but I was glad I had the shotty with me after some of the stories I was told down the pub later that evening....
In the end, it's a bit like the stories of the Yeti, Bigfoot, the Loch Ness monster etc.. It's nice to believe in the idea but we are not likey to see one in the flesh or even for one to be discoverd dead, been well photograhed or even caught alive, which you would have thought would have happened by