Tried this on a whim, and very glad. It is flavourful and refreshing. Must be made with a black rum to get that faint rum funk flavour. Citrus level perfect for this type of cocktail which slightly resembles a daiquiri. Perhaps might try a few drops of Difford's Daiquiri Bitters next time.
Since submitting my comment, we did add two drops of Difford's Daiquiri Bitters to the second half of the drink. For a full drink I would say 3 to 4 drops. It did soften the sharpness of the lime juice and make the cocktail a bit smoother.
I really rate this one, it's on my list of top cocktails. The proportions are about perfect for my taste. I use Plantation Original Dark Rum, and that seems to work very well.
Tasty! I reckon it'd be even better with a little less lime, which overwhelms the other ingredients. Will give it a go with 15ml lime juice if I make it again.