A dead one. Actually, only the skin was left - the previous occupier was long gone (I hope). It was barely visible in the foot high grass at the back of the house but after carefully pulling the grass out of the way I got the skin out. I also bashed the nearby grass with a big stick in case the previous tenant - of the skin - was still around.
Here it is laid out on the back of the pick-up:
And here on the patio wall:
A close-up of the head:
And another of the head:
Detail of the skin, in case anyone can identify it: