I've made this up for parties/barbecues/after the kids have gone to bed by putting together equal quantities of dark and pineapple rum and the other ingredients except lime in another bottle so it can essentially be constructed as a three ingredient cocktail - juice of a lime (approx.), 60ml Mixed Rum, 40ml 'Bells and Whistles'. Shook. Suddenly not so complicated to put together at the drop of a hat.

Genius. I doff my cap to you.