No one really speaks like that anymore, do they?
Except perhaps if they're English. And snobbish. Or belong to the Royal Family.
A modern equivalent would have to be something along the likes of "Don't make noise here". Somehow more authoritative, more demanding. Less polite, less pleasant.
It reads almost like the Keep Calm and Carry On poster (which, by the way, I'm sure is hanging in every hipster's inner city apartment wall right now). Yep, it has that same old-world flair for understatement, restraint and just that itty bit of stiffness.