Fill a mixing glass with ice cubes.
Add the gin, sweet red vermouth, and Fernet.
Stir well for approximately 30 seconds until thoroughly chilled and diluted.
Strain into a chilled cocktail glass.
Express an orange zest twist over the surface and use as garnish.
Ada Coleman reportedly created this drink for actor Sir Charles Hawtrey, who upon tasting it exclaimed 'By Jove! That is the real hanky-panky!' - giving the cocktail its name. Use a quality London Dry gin with pronounced juniper to stand up to the boldness of Fernet.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Hanky Panky.