This is a better cocktail than the similar but honey-sweetened De Rigueur Cocktail, as unless you have a very full-bodied honey, maple syrup's 'tang' sits...
Perhaps there is an inference in Mr. Difford's review that the "1930 The Savoy Cocktail Book" describes a recipe for a Brown Derby with maple syrup but "when made with honey this is a De Rigueur cocktail"?