“The Royal Clover Club emerged as a natural evolution of the classic Clover Club during the pre-Prohibition or Prohibition era, likely between 1920-1930. While the original Clover Club was a symbol of sophisticated gentlemen's club culture, the Royal variation transformed the frothy, airy character into something more substantial and luxurious. The "Royal" designation in cocktails of this period often signified the addition of a richer ingredient - in this case, egg yolk instead of egg white. The earliest known printed recipe appears in the Buckstone Book of Cocktails (circa 1925) and later in Harry Craddock's legendary Savoy Cocktail Book (1930), cementing its place in cocktail history.”