How far back does beer-making go in Britain? One 1980s archaeological dig at Kinloch on Scotland's Outer Hebrides Isle of Rhum found apparent residue from a long-evaporated beverage in pottery dating back about 4,000 years. Microscopic analysis detected pollen grains suggesting high levels of heather, with some meadowsweet and royal fern.
     Caroline Wickham-Jones, one of the excavation's archaeologists, said: "If you regarded them as a recipe then you can ask 'what would they make', and one of the things was heather ale as a fermented drink - but it might easily have been a mouthwash or something." 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.
     Large pots and evidence of heat-cracked stones have been found at Skara Brae, a 5,000-year-old settlement in the Orkney islands just north-east of Scotland. Local archaeologist Merryn Dineley believes that some of the pots were used for roasting malt - the germinated and heated cereal grains that ferment to produce alcohol.
     Jessica Smyth, an archaeologist and chemist at University College Dublin, says that proving conclusively that specific alcoholic beverages were drunk as far back as the Neolithic is extraordinarily difficult, if not impossible. Microscopic analysis of residues can never provide complete proof that an alcoholic beverage was once held in a vessel.
     Oliver Craig, an expert in bio-molecular archaeology at the University of York, says: "If you've got sprouted barley, that's good evidence for beer production." But such confirmation is difficult to find at pre-Roman sites in Britain. According to archaeologist Chris Stevens of University College, London, there is even a theory that between 5,300 and 4,400 years ago during the Neolithic period, Britons had a shortage of cereal grains for several hundred years due to climatic changes.
     Aside from ales brewed with fermented grain, it is possible that early Britons were fermenting honey. Wickham-Jones says the heather "ale" that may have been drunk at Kinloch would more likely have been of this type.

Edited from BBC (1 December 2016)