Snake Year Sherry is a type of wine seemingly available at the Five Dials Inn, so named for the multitude of adders that came down from nearby Clocktower Hill and settled in the inn's basement. At least one "lady adder set down some eggs" in one of the barrels which left a "bracky" odor. Prospero is told the story by a strange man in a brown robe - who later is discovered to be Roger Bacon (The Face in the Frost, 99).
Sherry is a fortified wine made from white grapes that are grown near the city of Jerez de la Frontera in Andalusia, Spain. After fermentation is complete, the base wines are fortified with grape spirit in order to increase their final alcohol content. As they age in barrel, they develop a layer of a yeast-like growth that helps protect the wine from excessive oxidation. Because the fortification takes place after fermentation, most sherries are initially dry, with any sweetness being added later. Many literary figures have written about sherry, including William Shakespeare and Edgar Allan Poe (notably, in his story "The Cask of Amontillado").
The beverage seems similar in concept to snake wine, an alcoholic beverage produced by infusing whole snakes in rice wine or grain alcohol. Such a concoction was first recorded to have been consumed in China ca. 1040–770 BC and considered an important curative and believed to reinvigorate a person according to Traditional Chinese medicine.
Author Quentin Dodd borrowed the name for Snake Year Press, his independent publishing venture.