A new Maker’s Mark bourbon is a rarity. The familiar squared off bottle, with its hand-dipped red wax top, was created by Margie Samuels in the 1950s, while her husband Bill perfected the mash bill for his “flavour vision” – soft red winter wheat providing a smooth, full-flavoured whiskey with sweetness dominating.

There have been a few experiments with alcohol strength and wood choice for ageing, but essentially, Maker’s Mark is Maker’s Mark. On average, it is aged for just over six years – three times as long as is legally required – to ensure there is no hint of sourness. However, until now, the distiller has also shied away from longer ageing in the Kentucky heat. Rob Samuels, grandson of the founders and now master whiskey maker, explains: ‘In the whiskey world, it is a misconception that older is always better. Because of the mild climate in Scotland, three summers there equals one summer in Kentucky, where it is intensely hot. While under-ageing whiskey is detrimental, so is over-oaking, introducing heavy, bitter tannins.’

However, for decades, Maker’s Mark fans have been clamouring for an older expression, so what was the solution? To create a limestone cave in a nearby hillside in which to age the bourbon. ‘The day we set off the dynamite was a nervous one, I must admit,’ says Samuels. ‘So, the cellar is carved into the hillside, with dry stack stone from the blast making up the front wall, and a roof with sod on top.’

Despite the explosion, it is avLEED-certified (Leadership in Energy and Environmental Design) structure. What’s more, it maintains a constant 52F (11C) temperature year-round. ‘We took some of those six-year-old barrels of Maker’s Mark and held them there for an extended period of time, the hypothesis being that we can slow down the heavy extraction of all those aggressive tannins, but continue the oxidation,’ Samuels explains.

Maker’s Mark Cellar Aged is 87% 12-year-old and 13% 11-year-old whiskey. It has a velvety mouthfeel, intensifying all those creamy flavours you might expect – vanilla custard, caramel etc. But there is a lovely level of fruit – baked stone fruit in particular – giving it extra character too.

Maker’s Mark Cellar Aged (£145) is available from retailers including Berry Bros & Rudd; makersmark.com