The Upper Crusts(1973)

Aristocrat Robin Seacroft lives carefree with his wife Phyllida, and their children Gareth and Davina, but all of this changes when he goes shooting with his father, the aged Lord Seacroft, who leaves his gun unattended. A curious rabbit sets off the gun and bang goes the former Lord Seacroft. Robin inherits his late father's title, but precious little else.