Interestingly, as with the Amsterdam, it would appear that Victor Bergeron ‘borrowed’ this recipe from a book called “The How and When” by Hyman Gale & Gerald F. Marco, published by Harmanson in New Orleans in 1937. I don’t have a copy of the book, but the ios app "Martin's Index of Cocktails" says that the recipe for the Bonnie Prince Charlie is on page 98 and is
40ml Cognac
20ml Drambuie
15ml lime juice.
I wonder how many more recipies Trader Vic borrowed from Hyman and Gerald?
Generally I don’t think you can improve on fresh lime juice in a cocktail. But try this one with yuzu juice instead. Yu-zu going to thank me (sorry - the cocktail is much better than that weak pun)