I clicked on the link in #10, and find that "between you and me and the lamppost" is there, and marked "Brit."
But for me (AE) it's a perfectly normal and familiar expression! As is another variant:
"between you, me and the china plate"
I don't know if either of those is old-fashioned. Maybe so.
When I read the OP, I thought the author was talking through his/her hat. Or only pretending to be a US native speaker. But who knows - I guess there are lots of regional differences. I was about to say "because the US is so huge" but then it occurred to me that there are pretty huge differences in language between, say for instance, north and south in England, which is less huge.