Stir the ingredients with ice in a mixing glass (50 times if using large ice cubes, 30 times if using small cubes). Strain into a chilled martini glass. Garnish with the pitted olive.
After the Second World War, gin was still king, but the amount of vermouth in a Martini began to diminish dramatically. By 1960, the Martini was a lethal 11 parts gin to 1 part vermouth.