That's the thing - they're unintended. This is the story of two decisions, which both had unintended consequences, and which led - one to the other.
William IV was the 3rd son of King George III, and no one ever expected him to be king. But between one thing and another, king he became, when he was 69, and he reigned for 7 years. His biggest historical claim is probably that he managed to stay alive until his niece, Victoria, reached the age of 18, and so could become queen without her mother being queen's regent. Queen Victoria did pretty well for the Monarchy.
Money seems not to have been William's friend. In fact, when Parliament - faced with the prospect of no heir to the throne, offered to pay off all of William's debts if he would leave his mistress of 20 years (and their 10 children) to marry someone royal and try to sire, he happily said yes. He married, and sired, but produced no heir.
When Trafalgar Square was built a few years after his death, the fourth plinth on the square was meant to hold a statue of William IV, but no statue of William seemed to exist. He died, rumor goes, without ever having had enough money for a proper statue of himself to be made. What an unintended consequence! In fact, Trafalgar Square was to have originally have been named King William the Fourth's Square, but, with no statue, they understandably changed plans.
The plinth meant for William's noble image was empty until 1999, when someone came up with the idea of having modern statues of contemporary heros there on a revolving basis. Great idea!
The current statue is of Sir Keith Park, who fought bravely in the Battle Of Britton in 1940. He was a New Zealander, and by all accounts a fine man and soldier. Here is his statue:
Doesn't he look handsome and dashing! Here's the statue from the back:
Unintended consequences will bite you every time.