It’s a profound technique to impart flavour. This is tempered by both the length of time a spirit is in the cask and how many times that cask is reused. That’s why a first-fill cask will have stronger characteristics of the original liquid than a tired fourth- or even fifth-fill one. It’s also why a six-month ‘finish’ – or secondary maturation – is usually less bold than a two-year one. But however long the finish lasts, it has a huge impact on flavour.

Sherry’s fortunes have ebbed and flowed over the years. The price and availability of the casks to distillers – not just in Scotland but further afield too – have tracked accordingly. Nowadays, since Sherry volumes have waned, bourbon casks are most commonly used in maturation warehouses around the world. That’s not to say the Sherry cask has become obsolete in whisky – far from it. Despite shifting fortunes, changes in legislation, fluctuating fashions in wine and the lure of Tequila, brandy and myriad other cask types, Sherry’s unmistakable compatibility with whisky continues. But times have changed since those transport cask days.

Today, most casks available to distillers are ‘seasoned’ with a purpose-made liquid that is often stylistically far removed from the classic Sherry categories. It is very rare to see a bodega cask used in maturation – and there’s barely any point. After being in use for multiple decades, it simply won’t have much left to give. Instead, it is typically these made- and seasoned-to-order casks that dominate Sherried whiskies. Unromantic perhaps, but the flourishing cask market provides distillers and blenders with a vibrant suite of options to choose from in their quest for flavour, right down to oak species.

From vast 500-litre butts, to tiny 50-litre octaves – the smaller the container, the more intense the influence – these bespoke creations give all manner of options for full maturation, finishes and to shape parcels for use in blending. The latter is becoming increasingly important. And that’s before we explore the different types of seasoning used in Sherry. Oloroso is the most common, with its nutty, dried-fruit power. Pedro Ximénez is also commonly seen, typically bringing sweeter notes. Fino, drier and more delicate, and the subtler Palo Cortado are also increasingly finding their way into whisky.

Through a tasting of almost 50 of the latest Sherried releases from around the world, three things jumped out. First, independent bottlers are thriving when it comes to the use of modern Sherry casks. They are in the market for casks that fall outside of a distillery’s signature profile; here they are pushing the flavour boundaries with quite spectacular results. Then it’s the turn of peated makers to shine. No longer is it all about pedal-to-the metal boldness. By harnessing Sherry flavours and controlling them, usually through a varied cask recipe, blenders are achieving remarkable harmony with smoky distillates. Finally, as with all things whisky, the big, established markets are no longer driving the narrative. From the UK to India, Australia and beyond, a new wave of producers are doing things their way. The most exciting of the cohort are showcased below. This is Sherry-cask whisky – but not as we know it.