pub, mild experienced a catastrophic fall in popularity after the 1960s and was in danger of completely disappearing from many parts of the United Kingdom. However, in recent years the explosion of microbreweries has led to a partial recovery, and an increasing number of mild (sometimes labelled 'Dark') brands are now being brewed. Most of these are in the more modern interpretation of "mild"...a sweeter brew with lower alcoholic strength. Light mild is generally similar, but pale in colour, for instance Harveys Brewery Knots of May. There is some overlap between the weakest styles of bitter and light mild, with the term AK being used to refer to both. The designation of such beers as "bitter" or "mild" has tended to change with fashion. A good example is McMullen's AK, which was re-badged as a bitter after decades as a light mild. AK (a very common beer name in the 19th century) was often referred to as a "mild bitter beer" interpreting "mild" as "unaged". Some breweries have revived the traditional high-gravity strong mild, with alcohol content of 6 per cent or so, the classic example being Sarah Hughes Ruby, brewed to a Victorian recipe. Burton Ale Burton Ale is a strong ale, produced in Burton on Trent since at least the 16th century, which is darker and sweeter than bitter. It has sometimes been used as a synonym for old ale. Old ale Old ale is a term applied to dark, malty beers above 4.5% ABV, also sometimes called Winter Warmers. Many have "old" in the name, such as Theakston's Old Peculier, Marston's Owd Roger, Robinson's Old Tom. Many brewers make high ABV old ales for bottling, some of which are bottle-conditioned and can mature for several years. Some of these stronger versions are known as barley wine. Stock ale is a strong beer which is used for blending with weaker beers at the brewery and not sold directly. The upper limit on strength for this style is about 11%–12% ABV. Porter and Stout Porter is a historically significant style developed in 18th century London, which is the ancestor of stout. English Porters and stouts are generally as dark or darker than old ales, and significantly more bitter. They differ from dark milds and old ales in the use of roast grains, which adds to the bitterness, and lends flavours of toast, biscuit or coffee. Variations on the style