Why is the ace of spades specially designed in many British card decks?

The elaborate design of the ace of spades in British card decks is not a matter of aesthetic choice, but a historical legacy of government regulation.

During the 18th century, the British government imposed a tax on the manufacture of playing cards to generate revenue. To ensure compliance and prevent forgery, authorities required that a tax authorization stamp be applied to a specific card in every deck. The ace of spades was selected for this purpose, and the tradition of featuring an ornate or specially designed ace of spades persists today as a vestige of that Stamp Act era.1