By chance, I saw one yesterday - driving into Truro, on the lane, 2ft to 2ft six high, three to four feet long, long thin tail, all fawn or leafy coloured, loping down the road, like a feline. Didn't get to see its head as it turned very quickly (sighting was only a few secs) and jumped into the undergrowth.
Long and short of it was, on advice from a nearby Llama farmer who I warned re her young, I called Newquay Zoo later and someone there who is plotting cat reports. He thought it likely to be a Puma.
There are several thought to be back when the Labour Govt tightened up on big cat/wild animals being kept at home. Many irresponsibles just cast them loose rather than own up - or rather and typically a Labour balls-up, they didnt have an amnesty, hence why the cats are out there.
There have been a number of sightings a few miles away but they can travel fifteen to twenty miles a day. They tend to live off small animals like rabbits, squirrels etc. and there is a substantial acreage of woodland nearby to give it cover.
The idea that they go around slaughtering lambs is a myth - they kill and drag their prey off into the undergrowth or bury it - and will eat it all before they move on.
Now if you go and walk the area, the zoo would be really interested if you found any of their spoor (turds) as this can be DNAed and give proof.....