The whisky, which survived the near closures of the distillery, was aged in two separate casks, a bourbon and an Oloroso sherry, which were married together to create a single malt, then transferred into a single refill Oloroso butt where it has remained to this day.

CEO Thomas Moradpour said: “This sale is a source of pride for everyone in the Ardbeg community who has made our journey possible. Just 25 years ago, Ardbeg was on the brink of extinction, but today it is one of the most sought-after whiskies in the world. That is a reflection of generations of hard work.

“While such a rare whisky is out of reach for all but one of our fans, we put the same passion and care into every bottle of Ardbeg as went into this exclusive single malt in 1975,” Moradpour added.

Over the next five years, Ardbeg will continue to mature Cask No. 3 in a secure location on Islay for its owner and every year they will receive 88 bottles from the cask, by 2026 they will possess a unique vertical series of Ardbegs from 1975, aged 46 to 50 years old.

Dr Bill Lumsden, who will oversee the cask’s ongoing maturation, said: “Cask No. 3 is a taste of Ardbeg’s past. So little stock survives from this era, its complex flavours are testament to the skill of the Ardbeg team who have cared for it over the decades.”

To celebrate the half-century of work behind this whisky, Ardbeg will donate £1million to causes on Islay.