Hi again,
The main point to stress is that wild and domestic are words used for a reason! A few big cats, pumas seem to be the agreed species, have survived the trauma of being "freed". I think you only have to think for a few moments to come to the conclusion that those that survived had already had experience of fending for themselves. In other words illeagally trapped and transported animals.
Take a few more moments to think about other likely species that were "freed" at around the same time. Monkeys and apes were the most popular exotic pet at the time and we have no colonys of either living wild in the UK. Vets prior to the legislation put to sleep more monkeys than any other exotic due to their aggresiveness as they matured. They were also the favourite, as babies, when the law was first implemented. Don't think twice about such an animal as a pet, just don't think about it!!

I have remembered the name of the lion found in a furniture store and later released to the wild in Africa by George Adamson, he was called Christian, make of that what you will.