As luck would have it, it was pissing it down on the August afternoon when The Book of Man visited the Barbados rum bar that Mount Gay have set up at the Madison Rooftop. We just about got the idea, as we put our hood up and dashed into the delightful wooden ‘Time Well Spent’ bar overlooking St Paul’s Cathedral, but as we retreated inside to try the menu we were thinking it’d need something special to get us into the Caribbean spirit.

Well, Jesus H F-ing  Christ (sorry, St Paul’s) if that wasn’t exactly what we got.

Bar Manager Eduard Balan has created a special, limited edition Mount Gay cocktail menu served exclusively from the ‘Time Well Spent’ bar, featuring the Madison’s unique twist on classic concoctions. And boy, does it work. We could talk about the Timeless Strawberry Mojito, which looks and tastes quite unlike any mojito we’ve had before with its colourless strawberry syrup and mint tincture, or we could talk about the Roasted Pina Colada, which uses coconut water and smoked pineapple to devastatingly tasty effect. But instead, let’s just talk about their Old Fashioned.

Or to be accurate, their Barrel Aged Rum Old Fashioned, for there is more to it than just a rum twist on the classic whisky cocktail. Yes, for their Old Fashioned, Eduard has used premium Mount Gay XO, sugar cane syrup and bitters, as you might imagine, but then put the drink in a Port oak barrel to age. When you order one, they dispense it straight out of this barrel, which is enormously pleasing but nowhere near as pleasing as actually tasting the thing.

It is spectacular. It’s an Old Fashioned alright, with all the richness and bitter complexity you’d want, but with an added sweetness that momentarily transports you from the City to the beaches of Barbados, with no actual decent weather required. It is a sensation.

We had four in 30 minutes.

Everyone should drink responsibly, and believe us, we didn’t want to drink four in 30 minutes but the thing is just so damn nice and we wanted to rigorously investigate why. Rest assured, our mind wasn’t playing tricks on us, it really is the best Old Fashioned you’ll get anywhere in London.

But you’d best be quick to try it, the ‘Time Well Spent’ terrace is live now but closes in September. Do not miss it!

Madison Rooftop.