I came across the phrase, "I don’t suppose you could lend me a pound?" in the short story titled "Chalk and Cheese," contained in "To Cut a Long Story Short" by Jeffrey Archer.
The phrase appears in the following sentence that Robin, the young brother who is gifted in fine art asks his elder brother at his one-man show at a gallery to lend him money: Robin brags his brother on his talent:
"One of the things I most admire about you," said Robin, "is that you have never envied my talent."
"Certainly not," said John. "I delight in it."
"Then let’s hope that some of my success rubs off on you, in whatever profession you should decide to follow." "Let's hope so." said John, not sure what else he could say. Robin leaned forward and lowered his voice.
"I don’t suppose you could lend me a pound? I’ll pay it back of course."
[Note: actually Robin has never paid back his repeated small loans from his good-natured brother.]
As I’ve never heard "I don’t suppose you could lend me a pound?" as an expression for asking somebody for lending money, I checked the usage of the phrase with Google NGram to find no result. The very beginning phrase, "I don’t suppose" sounds to me somewhat rounabout and disingenuous.
Is "I don't suppose you could lend me a pound?" a well-used pattern of phrase in Both England and America in borrowing money from someone whoever intimate with you or not?