Perusing my earlier columns, I notice the distinct lack of a few key styles that somehow eluded my careful discussion of British beer. I place the responsibility for this oversight squarely on you, the reader. In order to rectify this situation, I will present here my descriptions and recommendations for a few more classic English beer styles.
Milds and Browns
Milds are a style of beer with roots that go way back. Beers enjoyed by the likes of Richard the Lionhearted and the signers of the Magna Carta (also all the peasants we never hear about) are thought to have been similar in color and taste to modern milds and browns (though the malts were generally roasted over wood fires, imparting a smokiness that is absent in most of today's beer). Originally referred to as "mild" because of their lack of sourness (which came about as a result of aging), milds were traditionally served young, with a distinct lack of hop bitterness (which is why they are currently known as "mild.") Modern examples are low in alcohol (2%-4% ABV, or so), and are malty with a touch of raisiny fruitiness. They can be a bit chocolatey or nutty, but will not generally have the roasted character of porters or stouts. I haven't tried any American-made examples of this style, but I'm a big fan of both Brains Dark and Highgate Mild, both out of the UK.
Traditional English Brown Ales are a varied style, owing mainly to the different styles of brown that have developed in different geographical regions of Britain. They are similar to milds, but higher in alcohol (at 4%-5% ABV), and are characterized by a mild, sweet nuttiness with a very mild hop profile (examples from the north of England are generally drier and hoppier than the southern styles). My favorite example of this style is Samuel Smith's Nut Brown Ale, though there is one from the Anchorage-based Midnight Sun Brewery, Kodiak Brown Ale, that is also excellent.
Old Ale and Winter Warmer
These categories can kind of run together. These beers are very malty, moderately high in alcohol (usually up to about 10% ABV), with a nice hop balance. Typically they are fairly dark, with colors ranging from a deep, nearly opaque brown to a deep red-amber. Old Ales were traditionally aged in large vats, while winter warmers were brewed specifically for the winter months. Aged varieties often have some port or sherry-like qualities from the small amount of oxidation that occurs, and alcoholic warmness is not uncommon. Modern brewers often make a spiced "wassail" style winter beer and then slap a "winter-warmer" label on it, but this is not technically correct. Neither traditional old ales or winter warmer should have the addition of spices. Because these are alcoholic and (generally) well aged, you will find a lot of flavor complexity in these beers. Caramel is very common, with fruitiness that can be reminiscent of cherries or dried figs. Alaskan Winter Ale is a great winter warmer, while for old ale I generally look to some of the more venerable UK producers: Theakston's Old Peculiar in particular stands out to me.
Barley Wine
Barley Wine is the height of the brewer's art in England, in my opinion. These are high alcohol (10%-12+%), well aged, superbly balanced beers that traditionally are vintage dated and represented the best a given brewery had to offer. These beers have never been mass-produced, and many afficianados will cellar barley-wines for many years to develop their flavors.
As far as ingredients. Barley wine shares a lot in common with pale ales and bitters. They all use a pale malt as a base, with darker malts like Munich and chocolate added to help give a caramel-sweetness. Generally these beers aren't incredibly hoppy, Kent Goldings in particular (though American brewers have been branching into American hops for some time). The flavor profiles of well-aged barley wines are quite complex; the strong malt flavors blend with esters and a multitude of hop additions to form a beer that really can't be gulped down (the high alcohol content generally helps to discourage this as well). You can't go wrong with Young's Old Nick, and my favorite example comes from the Midnight Sun Brewery, in the form of the Arctic Devil Barley Wine (if you get the feeling that I recommend a disproportionate number of Alaskan beers, you're right - I'm from Anchorage, originally, and Midnight Sun produces some of the best beers I've tasted anywhere.)
Many American barley-wines are sufficiently different from the British style as to warrant their own category. These "American" barley wines are generally balanced more towards the hoppy side of things, and are often bigger all around. If you're feeling adventurous, try Rogue's Old Crustacean Ale for a good example of this style.
This wraps up my foray into British beer styles until I realized I've forgotten something important.