Cocktail, or highball? It’s really the latter; the drink really only has two ingredients: dark rum (here, Sailor Jerry Spiced Rum) and ginger ale, with more ale than rum. Garnish is a lime wedge.
There’s not much to the drink, but as a pre-dinner reviver, this one really hit the spot.
I’m not a big fan of flavoured rums, but on a fine, sunlit evening in St Ives in the best fish restaurant in the south west, the Porthminster Café, it really was a great pre-dinner drink.
* Naming note: I have spelled this drink with an ampersand. The original Dark ‘n’ Stormy recipe is protected by trademarks, filed by the rum company, Gosling’s, who invented the original drink, using only their Black Seal rum & a particular Bermudan brand of ginger beer (although they have recently changed to their own). If you’d like to know why, then an article in the New York Times will enlighten you.
Ice & Bitters 
Dark rum is the way to go and spiced even better. Love a dark and stormy.
Ah, but do you use Gosling’s? Or do you go off-piste with Sailor Jerry?