Phantom cats or alien big cats (ABCs) are a phenomenon of Britain seen over the last few decades: people out walking reporting sightings of large, wild cats (not native to Britain, whose native Wild Cat, found in Scotland, is not a great deal larger than a domestic cat). The best known of these are the so called Beast of Bodmin and the Surrey Puma. Though livestock have been occasionally killed, and numerous sightings reported, the evidence for these large wild cats is elusive. Occasional large cats are captured or killed, but it would be assumed they were one-off escapes from zoos etc, were it not for one major complicating factor: The Dangerous Wild Animals Act of 1976.
By the mid-1970s, a fad had arisen in the UK for keeping exotic animals of all types including big cats, as pets, and fears about large carnivores kept in people's houses and back gardens had generated pressure for something to be done to control this. The result was the Dangerous Wild Animals Act: this placed major restrictions on what animals could be kept, and the conditions under which they could be kept. Almost all cat species except the domestic cat were included under this head: bobcats, lynxes, jaguars, pumas etc. The net result of the Act was that anyone still wishing to keep these would have to build prohibitively expensive enclosures for them, or find a zoo that would take them, or have them destroyed. Zoos were swamped with owners trying to find a home for their animals; and the inevitable ensued. A number of owners confessed, some years later, that they had released their animals into the wild, to take their own chances, rather than see them destroyed. From 1976, and presumably for some time after, there were an unknown number of large cats roaming wild in Britain. Whether any of these survived and bred is unknown, but any now alive would be several generations after the original pets, and extremely shy of humans. There are people engaged in documenting sightings and attempting to determine what they may be, but evidence is mostly equivocal so far.
In January 2003, a dog was killed by a large predator in rural Wales; the body was discovered by an eye-witness who found the attacker still on the scene. He identified it as a big cat; further sightings in the area were suggestive of the animal being a panther. A post-mortem confirmed that the dog had been killed by a large predator; animal hairs found in the dog's mouth are to be subjected to DNA analysis.
Similar reports have been made in other places where such animals are not native—for instance, in the Gippsland region of south-eastern Victoria, Australia, where the culprit is claimed to be American World War II airmen who brought pumas with them as pets. Again, no evidence has been found other than shady sightings and dead livestock which could well have been killed by dog packs.