I found this on Doug Ford's Cold Glass blog. He cited its first appearance in Robert Vermeire’s 1922 "Cocktails: How to Mix Them." A pretty simple recipe but impressive in its balance of flavors, I think.
1 1/2 oz. gin
1 1/2 oz. dry vermouth
1/4 oz. maraschino
2 dashes orange bitters
Stir with ice and strain into a chilled cocktail glass. Lemon garnish.