Someone probably mistook a dog or a housecat. When was the last time there were wild large felines in Britain?
Very funny. I know that area. The so-called panther probably has more to worry about than the local populace.
There are regular Black Panther sightings in the UK. Often its just a case of forced perspective making a large black cat look as big as a Leopard. IIRC its about time for the save a black cat week in the UK. I have a Bombay Cat, which is a breed specifically meant to have the same proportions and coloring as a Indian Black Panther. Normally a small breed my Bombay, which I bought into the house about this time two years ago, has grown from a very tiny kitten to a very large heavy muscular Tom. There's not a single white hair on him any where, and even the nose and pads of the feet are solid black. His fangs overhang his lower jaw and his eyes are like new copper pennies.
Just keeping them on the latch should be sufficient. Unlike velociraptors I don't think cats, even big ones can open doors.