Although my flute skills aren't advanced enough for me to play hardly any of them, I follow the daily music pieces posted on flutetunes.com. A couple days ago, they posted a piece titled "The Queen's Shilling." Accompanying the piece, there's a short paragraph that explains that "the queen's shilling" or "the king's shilling" is "a historical slang term referring to the earnest payment of one shilling given to recruits to the Armed forces of the United Kingdom." Here's Collins' dictionary entry for "king's shilling."
Now that I've learned this term, I finally understand one of the lines in "Butcher's Tale" a bit better: "But the king's shilling is now my fee."