What’s the bartender’s secret to a great cocktail?

Run your eye down any bar menu of influence, and you’ll almost certainly see reference to Capreolus – the Cotswolds eaux-de-vie producer that’s become the secret handshake of the cocktail world. Bartenders have been using its unaged distillates of pear, quince, raspberry and plum like essences or perfumes – spritzing and droppering them into drinks like exquisite flavour bombs.

This rarefied liquid is distilled in a garden shed that’s unbelievably cramped – the ceiling is so low that founder Barney Wilczak has a permanent crick in his neck. But attention to detail is meticulous. All the fruit is grown within 50 miles and hand-sorted, berry by berry. When I arrive at the distillery in late August, Wilczak greets me in a T-shirt stained with cherries. Wilczak loves working with unusual and rare varieties: he talks about Helen’s Early perry pears and yellow egg plums. He’s also working on what he believes is the first eau-de-vie from English nectarines. “We put wine grapes on a pedestal,” he says, “but every plum, pear and apple is also different.”

Capreolus (from £68, capreolusdistillery.co.uk) is on bar lists from Brooklyn and Melbourne to Copenhagen. The 1,000 Trees Apple Eau-de-Vie – distilled from a single orchard with 1,000 apple varieties – is the spark in a smoky highball of whisky, sweet woodruff and honey at Mayfair’s Nipperkin. London’s new Peninsula Hotel uses the marzipan-like Perry Pear in a highball of cognac and Earl Grey tea. There is also a Sazerac starring the quince, which blossoms from citrussy lemongrass and orange zest into more sensual notes of rose, membrillo and white almond. “They’re so intense you only need 1ml or 2ml to transform a drink,” says one bartender. Another dubs them his “cheat code” ingredient, likening them to the code players use to unlock the next level in video games.

The product that saw Capreolus make the leap from darling of the fine-dining world to cult cocktail hack was the bestselling Raspberry. “It’s made with 10 times more fruit than most other berry eaux-de-vie,” says Wilczak. It’s like tasting in 3D: you get the berry, the leaf, and even a hint of bitter seeds. Bartender Remy Savage used so much of it at his Bar with Shapes for a Name in east London that he commissioned his own Capreolus eau-de-vie. Made from perfumed Egremont Russell apples, it will debut this winter at his Bar Nouveau in Paris. “I like Barney’s uncompromising nature,” he says. “He’s very loyal to the fruit. As a French person I like to think I know my eaux-de-vie, but when we blind-tasted Capreolus against some French examples we were just blown away.”

Would Wilzack consider a private commission? “Of course, if it was fruit we were excited about,” he says. “Our minimum working quantity is a ton.” And then he heads off back to his shed to see how the cherry eau-de-vie’s getting on. 

@alicelascelles