Is Von Bork's "I've been there" the idiomatic expression here, in "His Last Bow"?

Question

I’d like to ask about the sentence from His Last Bow by Conan Doyle.

“.. It was on my first arrival. I was invited to a week-end gathering at the country house of a cabinet minister. The conversation was amazingly indiscreet.”
Von Bork nodded. “I’ve been there,” said he dryly.

The first remark in the quote was spoken by Baron Von Herling, the chief secretary of the legation. And the second one is, as you can see, by Von Bork, an international spy.

I just wanted to make sure the meaning of this “I’ve been there”, the Von Bork’s remark.

This is of course an idiomatic expression which means “I have the same (similar) experience as you do” “I know how it is, how you feel because I too have gone through that”, right? I mean, how can it mean otherwise when the baron only mentioned “gathering in the country house of a cabinet minister”? Von Bork had no way to tell which cabinet minister the baron meant. Hence Von Bork, being a spy, had similar experiences where some English politicians spoke too candidly. Am I right?

Answer 1

The OED has a citation for this expression from 1877, some forty years before the publication of ‘His Last Bow’ in 1917.

colloquial (originally U.S.). to have been there (before): to have had previous experience of the activity or thing under review; to be fully conversant with or know something at first hand.

1877   Some reasons why I left off drinking whiskey, by one who has been there.   Saturday Evening Post in J. R. Ware, Passing English of Victorian Era (1909) 24/1

1913   But I'm not a young girl. If it's a question of the male sex, I may say that I've been there before.   A. Bennett, Great Adventure i. ii. 46

_{Oxford English Dictionary.}

Here’s more context from the 1913 citation:

JANET. You may tell me that people who go to a matrimonial agency stand a chance of getting let in. Well, people who don’t go to a matrimonial agency stand a chance of getting let in, too. Besides, I shouldn’t give a baby a razor for a birthday present, and I shouldn’t advise a young girl to go to a matrimonial agency. But I’m not a young girl. If it’s a question of the male sex, I may say that I’ve been there before. You understand me?

_{Arnold Bennett (1913). The Great Adventure, page 46. New York: George H. Doran.}

Here are two more examples also antedating ‘His Last Bow’:

“Don’t know so much about that,” muttered Sims. “It takes a clever man to hoodwink the British Navy. I’ve been there, and I know. A man doesn’t serve fifteen years in His Majesty’s marine without learning a few wrinkles.”

_{Hamilton Rae (1901). ‘A Little Surprise’. In The Royal Magazine, volume 6, page 420.}

I’ve dashed this letter off in a rush and really intended to have a steno type it, but she’s busy and will be for some days. So I trust you’ll pardon me for sending you this scrawl! And you a busy editor! Oh, yes, I’ve been there too. Published a newspaper once. Never again!

_{Anon (1913). Letter to Adventure magazine, volume 6, number 4, page 223. Via Google Books snippet view.}

Arnold Zwicky coined the phrase “recency illusion” for the phenomenon where a word or phrase is much older than one expects.

Answer 2

Yes, I think you're right

The most obvious thing for "I've been there" to be a response to is the last sentence of the other speaker's, "The conversation was amazingly indiscreet". As you note in the question, Von Bork would probably have been in similar situations. The use of "amazingly" conveys incredulousness (from the other speaker) at how indiscreet the conversation was. Von Bork answers "dryly" in a deadpan, indicating understanding and a shared poor opinion of such conduct. Thus it makes sense for Von Bork's dry understanding to mean that he's been in similar situations, demonstrating empathy for the other speaker's story.

Answer 3

I think the implication is that Von Bork is so knowledgeable that he can guess just which minister's country house is meant, and he has also been a guest at that house.

If I am correct, this not an idiomatic expression at all, but is meant literally: Van Bork has been at that house. I must admit that I do not have any clear evidence of this, but I think it is more logical than assuming that he is speaking metaphorically about a somewhat similar experience. After all the essence of Holmesian adventure is the ability (mostly of Holmes, but not always) to come to correct conclusions on what seems quite insufficient evidence.