Most people think of mixed beers through the Guinness-marketed blends of half and half (Guinness and Harp) and black and tan (Guinness and Bass). Although Guinness marketed these blends as a way to promote their products in the 20th century, those terms have a long history in English drinking that are not tied specifically to Guinness. A half and half, the most common, is merely a light ale and a stout or porter. It was very common to see stout and bitter but you can also find various other English beers in historical discussions. Although half and half generically describes the combination of light and dark beer, it is not the only one traditionally poured. Old Six is a blend of mild ale and barleywine/old ale (traditionally not different styles). My favorite must be mother-in-law. A blend of bitter and old.
The role of the publican in creating blends of beers declined with the rise of bottled beer. Porter, for example, was frequently served in the pub as a combination of aged, sour porter, mild (unaged) porter and some lighter and cheaper beer. After the desire for sour porter dropped off in the late 19th century there was still blends found of porter and a lighter beer (which became half and halfs). Brewers started bottling pre-blended combinations of porter and a lighter beer since the absence of sour beer meant no exploding bottles. Various brewers used blends of strong and weak beers to produce various strengths of ales, often blending old ale or stock ale with young bitter or pale ale. These bottled blends allowed brewers to stretch their supply of expensive aged or high gravity beers (the same reason publicans sold blends) and compete directly with the publicans. However, pub-blended beer did not die off completely. Well into the 1960s one could still find people drinking mixes that included mild, bitter, porter, stout and pale ale.
I find it unusual that with all of the craft beer available at bars the most one can normally find are blends containing Guinness or Blue Moon. The culture of bar-blended beer seems to have been left behind although mixed drinks containing craft beer and liquor seem quite popular. It's disappointing, really. I suppose our craft beers are flavorful enough that the blending is irrelevant. You don't need to mix a hoppy beer with a porter to make a hoppy porter. You can just buy one. However, I think there are some interesting combinations that are difficult to replicate in a single beer, if for no other reason than the fermentation in the single beer and the time for the components to blend together in a single beer makes for a different approach. Perhaps more importantly, you can't always find blends of sour or aged beers that also offer fresh, hoppy character. Incidentally, I think it would be interesting to see a taproom-focused brewery brew a set of strong and weak beers for the purpose of serving them both individually or blended. It could create interesting production advantages for a small brewery.
Ok, so why am I writing about this on a homebrewing blog? I think it's good, as brewers, for us to stretch our palettes and try different things. Plus I think it generally makes for tasty beer drinking. I also think it would be interesting to see a homebrew system set up that focused on blending, whether it is blending in the package or in the glass. I also believe that blending beer is something we will see grow as a practice in the craft beer community. Maybe not in the bar or in the taproom, but with all the barrel aging and sour brewing going on it presents a lot of opportunity for brewers to get creative and offer something unique beyond using the newest hop variety.