Interesting one this. Black cats in the UK keep coming up and nobody ever gets a solid explanation. I know Shropshire has had reports going back years, same with parts of Wales not far from there.
What size are we talking exactly? There's a big difference between a large domestic gone feral and something like a melanistic leopard which is what a lot of people assume when they say "black panther." Did it move like a domestic cat or was the gait different, more low and deliberate? That movement pattern is usually the giveaway.
I've spent time looking into big cat reports over here in Texas and the thing that always separates genuine sightings from misidentification is the witness describing the shoulder height relative to nearby objects, fences, hedgerows, that sort of thing. Did you get any sense of scale like that?
Also was this daytime or dusk? Would love to know if anyone else in the area has reported anything recently. These things dont usually pass through once and disappear, theres normally a pattern if you dig into local records.