One of the most inspired advertising mantras of all time, “Guinness is good for you” was so effective that, in the 1950s, an urban myth suggested you could get it on prescription. Even earlier, Guinness was often recommended for pregnant women and nursing mothers, and anybody deficient in iron. Though in recent years it has been marketed as an ale, Guinness is still the world’s best-selling dark beer or stout – that is, beer made from roasted malt or barley, traditionally strong and sometimes known as porter. These days it is having to compete with modern “craft brewers”, independent microbreweries that update and reimagine traditional styles such as stout and porter. Beer, in all its many forms, is still the most widely consumed alcoholic beverage, wit