Café Royal Cocktail Book by W. J. Tarling (1937, p.206)

2 dashesAngostura bitters — Angostura Bittersbase
0.5 partScotch whisky — Scotch Whiskybase
0.5 partsweet vermouth — Italian Vermouthmodifier
  1. Stir up and strain into cocktail glass.

Garnish: Squeeze lemon peel on top.