Ooh, Me Social Class's Dialect Is Slipping

A character is elegant or debonair, always speaking with just the right vocabulary and accent, so you just know he's one of the upper crust... Cor blimey, he just said something the way a lower-class person would say it! Maybe he hasn't always been so high-class after all?

This can work the other way around, of course -- it's just as easy to let slip that one was a member of a higher class as it is to let slip that one was a member of a lower class... or to let slip that one was a member of a class that isn't "higher" or "lower" but still isn't one's current class.

The trope is used most often with British characters (since Great Britain has a stereotype of having social stratification by class and Received Pronunciation is relatively easy to learn), but not exclusively so.

Compare with Ooh, Me Accent's Slipping. Contrast with Putting on Airs, where the character is faking the change in social class. (What, we don't have that trope, either? Here's the Merriam-Webster definition; somebody else make the page if we don't have one with a different name, please.)

Often used for comedic implementations of Sophisticated As Hell.

Film
""Come on, Dover, MOVE YER BLOOMIN' ARSE!""
 * My Fair Lady: Eliza's outburst at Ascot is possibly the Trope Codifier.

Live-Action Television

 * Battlestar Galactica: Gaius Baltar is the picture of elegance until he switches to his Aerilon accent in "Dirty Hands."
 * What's a trope page without examples from Buffy the Vampire Slayer?
 * Giles has a very dignified upper-class British accent -- except when he slips back into his old "Ripper" persona. It's most noticeable in the episode "Band Candy".
 * Spike is the opposite -- he speaks with a lower-class British accent almost exclusively. But when he reads his poetry in "Not Fade Away" it begins to slip, just a bit, and we hear a little of William's upper-class origins in it.

Web Comics

 * Girl Genius: The first time we see Trelawney Thorpe, Spark of the Realm in the actual story (as opposed to a side-story), she's the very model of a refined lady... until she makes a private aside to Wooster. (This may be one of those comedic implementations of Sophisticated As Hell.)