in the years following the First World War, though their popularity declined towards the end of the 20th century, apart from pockets of local interest such as in Glasgow with Sweetheart Stout. Beer writer Michael Jackson wrote about stouts and porters in the 1970s, but in the mid 1980s a survey by What’s Brewing found just 29 brewers in the UK and Channel Islands still making stout, most of them milk stouts. In the 21st century, stout is making a comeback with a new generation of drinkers, thanks to new products from burgeoning craft and regional brewers. Milk stout Milk stout (also called sweet stout or cream stout) is a stout containing lactose, a sugar derived from milk. Because lactose cannot be fermented by beer yeast, it adds sweetness and perceived body to the finished beer. Milk stout, which was claimed to be nutritious, was given to nursing mothers, and to help increase their milk production. The classic surviving example of milk stout is Mackeson's, for which the original brewers advertised that "each pint contains the energising carbohydrates of 10 ounces [284 ml] of pure dairy milk". The style was rare until being revived by a number of craft breweries in the twenty-first century. There were prosecutions in Newcastle upon Tyne in 1944 under the Food and Drugs Act 1938 regarding misleading labelling of milk stout. Dry or Irish stout With milk or sweet stout becoming the dominant stout in the UK in the early 20th century, it was mainly in Ireland that the non-sweet or standard stout was being made. As standard stout has a drier taste than the English and American sweet stouts, they came to be called dry stout or Irish stout to differentiate them from stouts with added lactose or oatmeal. This is the style that represents a typical stout to most people. The best selling stouts worldwide are Irish stouts made by Guinness (now owned by Diageo) at St. James's Gate Brewery (also known as the Guinness Brewery) in Dublin. Guinness makes a number of different varieties of its Irish stouts. Other examples of Irish dry stout include Murphy's and Beamish, now both owned by Heineken. Native Irish stouts are brewed by independent Irish craft breweries, most of whom include a stout in their core ranges. Draught Irish stout is normally served with a nitrogen propellant in addition to the carbon dioxide most beers use,