Big cat in Perthshire

I've been meaning to post this for a while, so it's slightly old news now, but I found this report of a big cat just outside Perth to be really interesting. Rather the usual panther or puma type sightings, it sounds a bit more like a Kellas cat, a hybrid between a domestic and Scottish wildcat, or possibly even a rabbit headed cat, the status of which is a bit more controversial.
My mum had an encounter with a large black cat outside of Luncarty (the other side of Perth to where this encountered occurred) around 20 years ago. Flicking through a book, she tenatively identified the Kellas cat as being closest to what she saw. One of her workmates spotted what was presumably the same animal a few days later, which crouched in a field and hissed at her. Could they range much further South than is generally assumed?
For more info on the Kellas Cats, I recommend My Highland Kellas Cats by Di Francis, who first brought them to national attention, and even attempted breeding them.