From William "Cocktail" Boothby's 1908/1914 The World's Drinks And How To Mix Them.
"Into a mixing-glass place a lump of ice, a dash of Orange bitters and a dash of cherry cordial. Add half a jigger of Sloe gin and half a jigger of Italian vermouth; stir until cold, twist in the oil from a piece of lemon peel, strain into a cocktail-glass and serve."
.5 oz Plymouth Sloe Gin
.5 oz Carpano Antica vermouth
dash Cherry Heering
dash orange bitters
Small, tart, sweet but complicated, and delightful.