Ah, phew, I would have been very surprised...
Well, people here occasionally see cats that are far too large to be domestic animals, especially in our local area. It's not always after having been to the pub. People, that is, not the cats, lol. A boy in my son's class saw one recently when he was out with his parents and a few days later it was spotted by other people. It is thought that they have either escaped from small private zoos, because people haven't been able to keep them properly or that they have been "abandoned" due to the dangerous animal act, which makes the keeping of dangerous animals far more complicated. (rightly so, of course!). As long as there are sheep and calves in the fields, these big cats can keep themselves alive in the wild, but tend to be shy or clever and keep out of humans' way the majority of the time.
BBC - Wiltshire - Moonraking - Big cats in Wiltshire
Weird Wiltshire - Big Cat Sightings
Off Duty Police Spot Big Cat (from Wiltshire Times)
www.ukbigcats.co.uk - The Definitive Guide To UK Big Cats