Famously, one 1980s archaeological dig at Kinloch on the Outer Hebrides' Isle of Rhum found apparent residue from a long-evaporated beverage. The pottery it came from dated back about 4,000 years. Microscopic analysis detected pollen grains, which suggested high levels of heather, and some meadowsweet and royal fern.
"If you regarded them as a recipe, then you can ask 'what would they make'," says Caroline Wickham-Jones, one of the excavation's archaeologists. "And one of the things was heather ale as a fermented drink – but it might easily have been a mouthwash or something."
Still, Wickham-Jones and her team enlisted the help of a Glenfiddich distillery to brew a new ale inspired by this potential recipe. "It was fabulous," she says.