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 isn't so high-class after all?

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 fake), but not exclusively so.

Compare with Ooh, Me Accent's Slipping. Contrast with Putting on Airs. (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 with 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.