There was a sighting about six years ago in Hainford, Norfolk. (In a field behind my former house, though I didn't see the animal myself) It was definitely a cat, black with a very long tail, and about as large as an Alsatian dog. It was trying to catch a pheasant. This was in broad daylight. Big black cats have often been seen in Norfolk. It's thought they are escapees from private zoos, or even illicit 'pets' chucked out, poor things, when they get beyond the cute kitten stage. It sounds to me like a puma (either the same one, or a pair) There are loads of rabbits, muntjacs, fallow deer etc for food. I'm not afraid of meeting one, they're very timid and wouldn't attack a human, just slink away. Some daft people in other areas mount an assassination posse, with shotguns, and try to find and kill them. I suppose some folk just enjoy exterminating wildlife!