I don’t know about the 1930s, but it was a common expression at one time. Nowadays, most people simply say “Right.” It tends to cross socio-economic boundaries. In the US, “Right” isn’t as common, as more people say “Yeah” or “Sure,” which also crosses socio-economic boundaries.

Quite, quite.

That’s an extremely stereotypical thing to say. I don’t think all classes of British society in the early 1930’s used the phrase “Right you are”. That’s like saying all Americans used the phrase “Far out, man” in the late 1960’s.

I think your instincts are correct. I don’t see it as something upper class English people of that time would say. As @SpatzieLover says, “Quite” would be much more of an upper class thing to say in agreement. (Not sure that the tweenie would say it either; sounds much more like the cabbie.)

For what it’s worth, E.M. Forster, in __“Howards End“_ (1910), writes it into the dinner conversation among distinguished guests at a restaurant.

And G.K. Chesterton has the wealthy Isadore Smythe say it in “The Invisible Man” (1911)

Only really in the same situations where Americans tend to use “Okay, then.” or “Sure thing.”

It can’t always be substituted for ‘yes’. It’s usually used as a kind of final agreement. Most commonly you’re understanding and agreeing with a suggestion, and conclusively accept it, with an implication that the action will be performed immediately (if not otherwise specified or implied).

e.g.
“Driver? We wish to detour to the Hotel Parisienne immediately.”
“Right you are, sir.”

“James, I think we should send a telegram to our good friend in New York.”
“Right you are, brother. I’ll compose one now.”

“If you need any refreshment, Mr Stephenson, my wife will be happy to oblige. Just let us know, we’ll be on the veranda.”
“Right you are.”

Else, when dealing with facts rather than suggested activities, it can be used as Americans use: “You got it.” & “You betcha.”
Usually as “Right you are, Mr. Mandeville!”

In this case, I consider it much more likely that the upper-classes would say “Quite.” or “Quite right.” or “Exactly.” or, especially if acknowledging before countering, “Undoubtedly, ...”

However, “Quite” can often be used in a manner which suggests agreement with a statement, but not its manner (eg a Gentleman agreeing with his cabbie), whereas “Exactly.” suggests exact agreement. Naturally, it could also be used for an opposite, ironic effect.

e.g.
“I fink the bloke’s a crook and ‘e should be ‘anged”
“Quite.”

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Sorry, I haven’t answered your actual question very well at all.

I do have some more relevant suggestion; I think it’s more likely that the user of the phrase will be speaking to someone above or equal to his social standing. It’s a very difficult concept to explain, but it would sound rather pretentious of a working-class person to say it to one of their fellows, and also rather “chummy” of an upper-class person to say it to a cabbie for example. More likely to say it to his butler though, who is more personally close. I’d say its definitely reasonable to hear middle-class people saying to each other, and not uncommon for the upper-classes to use it between themselves (informally), but usually in the first sense, as described above.

Now I don’t have any evidence for the above, but it’s just my gut feeling, so take it as you will.