I was always led to believe the big cats killed by getting into the neck/throat, and sometimes, in jaguars, the head? There's no bite wounds on this in those areas, and as another has stated, that carcass looks like it's been clean cut in half, even the grass where the back end would have been is clean as a whistle? To me it looks like a half butchered carcass dumped on the lawn, certainly not evidence of big cats in the UK....
Yokel