Mild is one of the most traditional beer styles which is enjoying a revival in today's real ale market. Usually dark brown in colour, due to the use of well-roasted malts or barley it is less hopped than bitters and often has a chocolatety character with nutty and burnt flavours.
Cask conditioned Mild is a rarity in a lot of parts of the country, which is a crying shame, because Mild is a distinctive and tasty beer. Mild is one of, if not the, oldest beer styles in the country. Until the 15th century, ale and mead were the major British brews, both made without hops. Hops were introduced from Holland, France and Germany after this time. This also started the trend on reducing the gravity of ale, as the Hop is also a preservative, and beers had to be brewed very strongly to try to help preserve them. The hop also started the rapid decline of mead, which is only made in a very few places today.
So what is Mild? It is a beer which has tastes and textures all it's own. Basically it is a beer that is less hopped than bitter, etc. The darkness of Dark Milds, such as Greene King XX Mild, comes from the use of darker malts and/or roasted barley which are used to compensate for the loss of Hop character. "Chocolate ", "fruity", "nutty" and "burnt" are all tastes to be found in the complexity of Milds. However, not all milds are dark. Yorkshire brewed Timothy Taylors Golden Best is one of the best examples of a light coloured mild, as is Bank's Original, the name changed from Mild to try to give it a more modern image. In Scotland, 60/- ale is similar to mild (Belhaven's being a good example).
Milds today tend to have an ABV in the 3% to 3.5% range, with of course some notable exceptions. In fact, a lot of the Microbreweries who try their hand at mild are bringing the alcohol content back up somewhat! Mild wasn't always weaker though. In the latter half of the 19th Century, milds were brewed to about the same strength as bitters as a response to the demand for a sweeter beer from the working classes and in those days most bitters were around 6 to 7% ABV.
During the First World War, malt rationing and pressure from the temperance movement led to brewers rapidly reduced the strength. Following the Second World War, as prosperity returned, mild's popularity as a cheap ale began to fade, not being helped by being kept badly in run down pubs as the Big Brewers began to heavily promote their keg lager brands. Coupled to this was a gradual, but steady decline in heavy industry in the North and Midlands of Britain, mild's great marketplace.
By the 1970s, the keg lager boom had seen mild's share of the market fall to around 13% and it was a shame to see a bland gassy and overpriced product, which was generally weaker than the mild it was trying to oust, succeed in many cases.