Drambuie snapped up by Glenfiddich owners

The family behind Glenfiddich single malt and Hendrick's gin has bought Drambuie, the whisky liqueur fabled to have been concocted by Bonnie Prince Charlie.

William Grant & Sons, one of Scotland's few whisky makers still in family ownership, announced it had bought the Highlands liqueur to bring the brand to “an entirely new generation of consumers”.

Earlier reports claimed that the Drambuie brand was expected to be sold for £100m, but William Grant declined to reveal the sale price.

Around 250,000 cases of Drambuie are sold every year, but while the liqueur is a common feature in drinks cabinets in the UK, the US, Canada and Australia, it is virtually non-existent in Asian markets, where demand for premium western spirits has soared.

Drambuie claims its origins date back to 1746, when Prince Charles Edward Stuart (Bonnie Prince Charlie) was on the run following his crushing defeat at Culloden the previous year. The Jacobite pretender is said to have passed on the secret recipe – a blend of whisky, honey and spices –to John MacKinnon, a clan leader who helped him flee the Isle of Skye into exile in France.

Many regard this version of events as little more than shrewd PR, devised by the MacKinnon family to boost sales of the liqueur, which they launched on the Scottish mainland in 1909 and in the US after the first world war.

In his 2003 travelogue around Scotland's distilleries, Raw Spirit, Iain banks suggested the story was a tall tale. “There seems to be some dispute over whether Prince Charlie already had the recipe and gave it to the MacKinnons as a thank you, or they already had the recipe and just made canny use of the romantic connection. I prefer the latter.”

William Grant is expected to exploit that story to promote the drink in new places, although it fears access to new markets could be undermined by a yes vote in the independence referendum on 18 September.

William Grant & Sons said it backed the stance of the Scotch Whisky Association, which recently highlighted the “risks” of independence to its export-focused industry. “We see those risks as being around the loss of global support for those exports, about Scotland's potential status and likely influence in the EU, and about the currency and the potential fragmentation of the UK domestic market,” the industry body's chief executive, David Frost, said in June.

William Grant, which has its headquarters in Richmond, Surrey, as well as distilleries on Speyside, is understood to have donated at least £100,000 to the Better Together campaign.

Drambuie is bottled in Glasgow and William Grant has no plans to make major changes, while it reviews the business.