Rum Swizzles were the drink of choice at what was purportedly the world’s first cocktail party held in London in 1924, described by novelist Alec Waugh (elder brother of Evelyn Waugh, and author of The Loom of Youth and Island in the Sun).
Alec Waugh claimed that he invented the first cocktail party in the world by serving Rum Swizzles to astonished friends, who thought that they had simply come for tea at his flat.
For more background, see: http://vinepair.com/articles/history-of-the-cocktail-party/
Bloomberg’s recommended variation is known as the Queen’s Park Swizzle, which was first concocted in Trinidad in the 1920s.
For more background on the Rum Swizzle, see: