This story isn’t particularly nice for the cat, but childhood wasn’t particularly nice for Victorian children, so…

This is a very strange, but thoroughly Victorian, tale about a giant demon cat who jumps aboard a naval ship, shrinks down to normal-cat-size, does normal cat mischief, and ultimately, suffers greatly & gruesomely for choice of napping spot. The shock value of the ending is reminiscent of the subject matter of the contemporary sensationalist penny dreadfuls.
A children’s book by design, the explosive ending speaks to the different perspectives of childhood between the 19th and early 20th century compared to our own. Brutal literature reflects a brutal time period. Untreatable diseases, the consequences of industrialisation & child labor, overcrowded urban areas and crime, these quotidian horrors that children faced perhaps reframe the Demon Cat into a comparatively whimsical story for the Victorian child. Like with many Victorian children’s stories, the moral of the story is to not be like the Demon Cat: show restraint and respect, avoid being overly curious, do not nap in a “ripe Stilton” cheese, try to not be a nuisance, and you may not get blown up by a cannon.