Treacle is a classic british ingredient, a dark syrup made in the sugar-refining process. Legendary london barman dick bradsell invented this cocktail in its honor, bringing those rich molasses flavors to the cocktail glass. Apple juice is a rare ingredient in good cocktails; its usually too watery and weak to make a balanced drink. Here, bradsell floats it atop the drink, which offers a brilliant contrast between the juice and the string dark rum beneath it.