Sheffield, a city with a lot of terraced housing, is particularly prone to "big cat scares", the usual story being that it moves around in the roof-spaces of the adjoined terraces. I lived next door to a lovely little old lady who was convinced that the noises in her attic were from an errant leopard rather than a pigeon.
That's hilarious. Have they checked there's not something in the environment turning people mad? Is it even common for terraced houses to share roof space without a dividing wall??
They tend to be built in 4s, with a covered alleyway between the two middle ones (a "gennel" in local parlance), the roof ends have supporting walls of course, the middle ones sometimes have brick, sometimes just wood and a panel-wall to support the (always slate) roof proper.
As to madness, almost certainly, they're all barking (in an agreeable way).
