Up to a certain point (quote)

A few weeks ago I read an article (I think it was about foreign policy, maybe China) where there was a story quoted about a man who always went along and never contradicted. when the other person was right he’d say “yes sir” and when the other person was wrong he would always say “up to a certain point”.

-The capital of Japan is Yokohama isn’t it?
-Up to a certain point

The story was quite funny and now that I try to find it I can’t. I have searched the internet in vain. Can anyone please help me find the source of this story?

Up to a certain point…

My WAG would be that it’s not on the Internet because it’s just a joke, and search engines tend not to turn up simple jokes unless somebody has it posted on his website.

It sounds like a pretty standard after-dinner speaker kind of joke to me. Like “5,000 Toasts and Jokes for All Occasions,” that sort of thing.

Well, it took me two and a half years but I am a persistent person and, finally, found the answer. The quote is from the 1938 novel Scoop by Evelyn Waugh, the author of Brideshead Revisited.