Probably you've heard that Prince William and Princess Kate have laid down an official complaint against pictures taken when they were on a (private) holiday. A French magazine turned up with pics of Kate in monokini, and some others.
Now my idea is that Kate should have known better if she wanted to be royalty. If you marry a prince, who is heir to a throne, you KNOW you won't be able to live as the ordinary girl next door. And thus you should be aware - especially in the case of the English royals - that the paparazi are everywhere and will watch all your doings with BIG telelenses.
So even when you are at a private party or vacation, you should behave appropriately like this:
Don't go swimming naked or half naked, because even when you think you are alone, you probably aren't.
A princess should always dress in a decent manner (and I'm no prude). They can wear shorts, if it's not too short (bermuda?) and a tanker top, as long as it doesn't show anything of your bosom.
Just the same goes for teacher, I think. You can't face a class full of young men and women dressed like something out of a nightclub.
What is your idea?