With one of the filming locations being London Zoo, there are some nice big cats on display. These super predators are also a visual clue to the nature of the movie's dysfunctional family.
An interesting shot of a relaxed tiger looking harmless with the bars of its cage almost removed by the camera is followed by that of a caged cheetah which hunts by day. This cat symbolism is very intentional.
Back in Oakley Court (which, in reality, is around 25 miles away from London Zoo), the family's black and white cat makes several appearances although mainly in the kitchen.
Product placement or realism? You decide. Cats don't eat porridge.
Notice how it's Sonny (Howard Trevor) who holds the pet cat since he seems to be the most "domesticated" within the bizarre family situation.
There's also a Beatrix Potter-style cartoon cat stuck on a cupboard door, but you can have fun spotting that one and its implications yourself.