These scions of the Guinness family:
More recently, in 2004, Kindersley went into his local branch of Waitrose . Asked by the checkout girl if he would like some cash back, Kindersley (who was unfamiliar with this transaction) replied: “That’s really awfully sweet of you, how kind.”
He suggested £50, which he took across the road to the betting shop, investing it on a 10-1 shot which duly won its race. He then returned to the store to tip the checkout girl £10 for her kindness. For good measure, he gave £10 to the other girls on the tills as well. It was only when his credit card statement arrived that he understood the nature of “cash back”.