Re: "The Singapore Sling is a classic cocktail without a classic recipe; the recipe was lost during Prohibition."
What blatant poppycock! The Singapore Sling was invented at the Raffles Hotel in Singapore in the early twentieth century. Singapore was then a British Colony, and the Raffles an important British hotel. I can assure you that American prohibition had no impact whatsoever on British or British-colonial drinking habits or recipes.
With most cocktails, variations on the recipe evolve over time. The Singapore Sling is no exception. These variations do not indicate that a "true" recipe was lost because of American Prohibition!