The British government traces its legitimacy to the crown, and Diana, Princess of Wales, has been a very visible symbol of the crown in recent years. Legitimacy is indespensible.
Legitimacy is the difference between a State and an organized crime syndicate.
I can confidently predict that, as irrelevant as the monarchy is to actual British government, and as unworthy is the conduct of most of that royal family, Britain would become ungovernable if the monarchy were abolished. Amid all the hype surrounding the tragic death of Diana, Princess of Wales, it is worth considering why anybody would care. People are interested because Princess Di was a celebrity. She became a celebrity by attaining royalty, and she attracted a lot of attention by frequently appearing in public, and by being photogenic. The question remains, Why would an American care about the royal family of some other country, especially when the monarch has no actual governing authority.