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.

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.
 * This, mixed with Ooh, Me Accent's Slipping, was the main running gag of old Radio Rochela sketch "Rafucho el Maracucho". Almost every sketch was about how the titular Rafucho, a very crass man from Maracaibo (which is the Venezuelan equivalent of Texas and Osaka rolled into one), ended whenever his cousin/eventual romantic interest Lilita was working; thing is, Lilita was always trying to pass as somebody classier/foreigner than her humble origins were, and she tried to maintain the facade until either Rafucho's taunts or his atrocious manners fed her up and made her explode and regress to her original maracucho accent.

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.)