For decades, there have been reports of big cats roaming the British countryside. Some people believe that these animals are escaped exotic pets, while others believe that they are wild animals that have been living here for centuries.

Now, a documentary filmmaker claims to have DNA evidence that black leopards are present in the countryside, after collecting a sample of hair from a barbwire fence at a farm in Gloucestershire and having it lab-tested.

But while we wait for the study to be published, is there any evidence of it previously? Andrew Kitchener reports.

Are any big cats living wild in the UK?

It depends what you mean. Non-native wild cats may escape or be released into the wild and survive, but most are recaptured or eventually die. Breeding animals are very unlikely.

But what about 'supposed' photos of them? Why aren't photos of big cats considered evidence?

Photos and videos are often out of focus and low resolution, producing fuzzy images when enlarged. We automatically fill in the ‘gaps’ that are created in poor-quality images with what we have previously seen and what is suggested by the photograph.

How else can photos mislead us?

Something of a known size may be used as a comparison with the ‘big cat’, but these photos could be taken from a different place or using a different lens, leading to distorted size and shape. It can be difficult to judge distances and how big something really is, leading to an exaggeration of size.

Give an example.

In June 2009, an alleged black panther was filmed walking along railway lines near Helensburgh, Argyll. The grainy, shaky footage makes it difficult to identify the cat, though it’s clearly not very big compared to the railway tracks. Later footage, using a different camera, showed a perfectly normal domestic cat.

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Any others?

A trailcam photo of an alleged big cat taken in July 2016 in Gloucestershire was compared in news reports with a photo of a fox in the same location, but in fact the photos confirm the animal as the size of a domestic cat. Grainy, out-of-focus footage of an animal identified as a lynx reported in November 2016 was nothing more than a long-tailed cat. Lynx are bigger and have short tails.

What would be proof of big cats living in the UK?

The best evidence would be high-quality trailcam images or a road casualty – a post mortem could establish conclusively whether or not it had been living in the wild.