The Millionaire Cocktail is a classic cocktail, one of those that have stood up to the tests of time and been adapted into many forms. This recipe is the original Millionaire Cocktail No. 1 from the Harry Cradock's 1930 "Savoy Cocktail Book". The drink is a lovely mix of sloe gin, apricot brandy, and Jamaican rum.
There are quite a few different recipes that specify brands and change the ratio. You may also come across the whiskey Millionaire, which can lead to some confusion.