Some background first: As I was reading some past answers on English L&U, I came across this old question, where the top accepted answer maintained there were distinct class differences in the use of the expression "cheers" amongst the British. Some people disagreed with the tone of the accepted answer; in particular, the answerer was accused of stereotyping in the comments, and his response was challenged by another user who in response gave what he obviously considered a laughable stereotype of upper-class English speaking: "Top drawer, what?!"
I remembered then that I'd often seen and heard "wot wot" used in the same mocking way. For example, one of my childhood friends, if he wanted to play mock-Briton, might say something like: "Tally-ho, old bean, wot wot?" Googling informs me this usage isn't just idiosyncratic on his part; evidently, lots of people are interested in the history of this phrase, as Google suggests "wot wot British" as a query, with IMO few helpful responses on the first couple of pages.
So is this impression accurate: Did upper-class (or any class, for that matter) British really use to speak like this, i.e. is this expression mocking because it's so archaic that it seems funny now? If not, where did this caricature come from?
Best Answer
Best of my knowledge, the "wot wot" verbal tic is specifically British, Georgian and definitely an upper-class marker.
Indeed, one of the most famous adept of this "wot wot" verbal tic, was George III (the one of the American Independence), as seen in the film "The Madness of King George" (recommended).
I did not count them but the script puts tens of these "wot wot" in the mouth of actor Nigel Hawthorne. And they seem to apply indifferently to both insignificant everyday life events and to important political matters. This trait contributes to depicting a King in constant need of approbation from his entourage, often assailed by doubts that he is fit for the task laid on his shoulders, at times prone to hiding behind authoritarianism but actually unsure of being genuinely perceived as the first really English king of the Hanover dynasty.
Significantly enough, he is, best of my recollections, the only character in the film afflicted with this verbal tic. This is by no means sufficient to conjecture that he might have started the trend. However, if the film is to be trusted on the subject, he must certainly have amplified it. Even more so considering the length of his reign (as there is apparently a rule about mad kings in both France and England that they should enjoy a long reign ;-) )
In some of today's British upper-class circles, you can still hear it in the form of a single "what ?", added at the end of a short colloquial sentence as a short way of asking "what do you say ?" in the context of an invitation.
An example usage would be: "Let's go for a walk, what ? [what do you say]" or "a storm is brewing, what ? [what do you think]". Since it is perceived as old fashioned and slightly snob, it is gently mocked in plays, shows and popular culture and has also now become a cliché.
Either around the time of "King George" and the "red coats", or may be later (but that would not be "wot wot" but "what") this stereotype might have been extended in the United States to the whole British people (conjecture again I'm afraid).
As an aside, there are in English, many other regional verbal tics whereby people interject a word at the end of a sentence in order to ask for approbation.
"It's gonna rain again, lah. I'd better stay at home, one". In this case it means something like "Don't you think ?" or close to "I'm pretty sure about that."