Porter, a type of dark beer that first saw life in the 1700s, built London’s greatest breweries, slaked the thirsts of America’s revolution-minded colonists, and then traveled the world, morphing as it went to meet the changing needs of time and place. Porter remains a beer style that is nowadays firmly established in the consciousness of the beer-drinking public all over the world, even if it is difficult to know what it actually tasted like in its heyday. Today, the best renditions of porter are well balanced and aromatic, with predominant notes of rich chocolate as well as hints of coffee, caramel, nuts, and sometimes a faint smokiness, combined with an often dry, even slightly acidic, finish. The origins of this beer style, however, are about as opaque as the beer itself. The most persistent and fanciful tale, for which most objectivists agree there is very little hard evidence, speaks of the “invention” of the porter style by Ralph Harwood, the owner of the Bell Brewhouse in Shoreditch, East London, England, in 1722. See harwood, ralph. Allegedly, Mr Harwood’s beer was created for the convenience of a publican who ran the Blue Last, a working class watering hole on Shoreditch’s Great Eastern Street. The Blue Last was then frequented mostly by “porters”—strongmen for hire, who would carry loads of produce, fish, and dry goods on their backs from merchant storehouses to the city’s many public markets. In those days, beer in pubs was invariably served cask conditioned, and it was often served as a mix from several casks, or “butts.” When the barman poured beer from a butt, the stream of beer was referred to as a “thread”; a blended mug of beer might contain several threads. One of the oft-mentioned popular blends of the day was called “three-threads.” See cask conditioning and three-threads. There were several reasons for the practice of mixing different beers right into a patron’s mug or tankard on the premises. Given the uneven quality of brewing grains and malts—a problem that was only remedied starting in the early 19th century—beer flavors were not always predictable. Thus, blending a single beer from several casks on the spot allowed the publican great flexibility in catering to his clientele’s tastes. Mixing threads was also a way for sneaky publicans to sell rather than dump slightly “off” or acetic barrels by diluting them with one or more drinkable threads.

Mr Harwood allegedly decided to do the blending for the publican right at the brewery; this would obviate the need to take the time to blend several types of beer into each glass. He concocted a mash—probably mostly of brown malt—that represented a mixture of the publican’s threads and called it “entire butt.” It bundled the flavors of several butts into a single, labor-saving, pre-fab “entire” ale that could be poured as a single thread. Because this new beer quickly became the favorite of the hard-working and hard-drinking porters, it eventually became known by the occupation of its best customers—and the name “porter” stuck for the beer.

Thus goes the happy tale of the birth of porter, and it seems vaguely unfortunate that it is probably not true. Three-threads was a reality, but it seems that porter was in fact something else. It is also true that porter was often a blend, and this is where the various stories may have crossed paths and melded. Porter almost certainly emerged as a variant of a beer widely referred to simply as “brown beer,” for which a number of early 18th-century recipes exist. Porter seems to have begun its reign as an aged, or “stale” version of brown beer, and this aged character became prized during the 1700s. In 1773, in The Complete English Brewer, George Watkins writes of larger, well-experienced porter breweries: “Thus, in brewing porter, they make three and sometimes four mashes; strengthening them with a little fresh malt, or running them as they call it a greater length, that is, making more beer from the same malt, according to their pleasure. These several worts they mix and make the whole of such a strength as experience shews them porter ought to have; and this they work up and barrel accordingly. In the same manner, if a butt of porter be too mild, they will throw into it a small quantity of some that is very strong and too stale; first dissolving in it a little isinglass. This produces a new tho’ slight fermentation; and the liquor, in eighteen or twenty days, fines down, and has the expected flavor.”

Thus, we do see early mention of porter as a blend within the brewery; this was a practice that was not at all unusual in other brewing cultures of the time. See blending houses.

The American colonies imported porter from London, but as matters became heated between England and the colonies in the late 1760s, American porter breweries took up the slack. George Washington’s favorite porter was brewed by one Robert Hare of Philadelphia; we still have Washington’s letters extolling its virtues and ordering extra stocks after a fire at the brewery in 1790. Porter was a favorite style in the early United States and was still widely brewed before lager beer pushed it aside in the mid 1800s.

Back in London, by the end of the 18th century porter had become truly big business. Porter brewing reached its peak in London in the 1820s, by which time it had become arguably the first mass-produced commercial beer. In Ireland, too, the original brown porter of London became a popular beer. There it was known as “plain porter,” a beer that continued to be made under that name by Guinness until 1974. To this day in Ireland, you still hear the occasional older gentleman ask for “a pint of plain.” See arthur guinness & sons. As the demand for porter grew, not only among the laboring classes but also among the better off, so did the size of the breweries that made it. Some breweries began to specialize in this single beer style and became very prosperous enterprises. In the first half of the 19th century the Truman, Hanbury & Buxton Brewery, for instance, had managed to become Britain’s second largest brewery purely on the strength of its porter, of which a record shows it produced about 305,000 hl (260,000 US bbl) in 1845 alone. See truman, hanbury, buxton & co. As the Industrial Revolution produced one new mechanical marvel after another, London’s porter breweries put them to use with startling speed and ingenuity. Steam engines were in use in London’s porter breweries within months of being patented.

Because the best-tasting porters were often matured in holding tanks for months or even up to a year, some of the aging vats became truly gigantic. Some vats were so large that breweries could serve occasional promotional dinners for their patrons inside them when they were empty. The world record in wooden fermenters at the time was set by the Meux Brewery of London, whose largest wooden porter vat could hold about 32,500 hl (roughly 27,750 US bbl). See meux reid & co.

On a day in October 1814, however, one of the giant Meux vats suddenly burst, causing rivers of porter to rush through the adjacent streets, crushing houses and drowning several people in beer. The final tally of the destruction included eight people dead from drowning, injuries, or alcohol poisoning of those who took more than their fill from the unexpected free beer running in the gutters. Today, in London’s Chiswell Street, there remains an events venue called “The Brewery,” and it is still possible to hold large gatherings in a space that was once held the Whitbread Brewery’s huge porter tuns. The Whitbread Porter Tun Room is one of the largest unobstructed indoor spaces in London.

Despite the huge popularity of porter in its heyday, we have only a vague understanding of how it must have tasted. The best we can do is to draw some reasonable inferences. The original porter, no doubt, was a deep shade of brown to mahogany, made from a foundation grist of the standard floor-malted brown malt of the day with some smoky notes from the kilning of the grain over open wood, straw, coal, or coke fires. Straw-dried brown malt was considered the best because it had relatively little smoke flavor. Either deliberately or inadvertently, some portion of the grain bill may also have been popcornlike, so-called blown or snap malt. See snap malt. Brown malts were sometimes merely toasted, sometimes quite dark, and often somewhat burned. They were usually left with only a portion of their original starch remaining for subsequent conversion to sugar. Aside from this, depending upon changing laws at any given time, colorings were widely used in porter, a favorite being a type of burnt sugar syrup. Licorice was also a popular additive and colorant. Porters appear to have been highly hopped, although the bitterness would have mellowed over months of aging.

However, there must have been a microbial story to tell as well. Considering the long aging of porter in vast wooden vats, it is impossible not to postulate that these vats were also breeding grounds for wild yeasts and bacteria, including probably lactobacillus and what we now call Brettanomyces, both of which have notable effects on the flavor of finished beer. See brettanomyces, lactobacillus, and wild yeast. Whereas lactobacillus produces tart lactic acid, the “wild” yeast strain Brettanomyces is responsible for the barnyard and sweaty horse blanket notes we have come to associate with many Belgian spontaneously fermented lambics. See lambic. This interpretation is supported by that fact that Brettanomyces was first identified not in Belgium, but in Britain, in the secondary fermentation of a British stock ale, by N. Hjelte Claussen, the then director of the Laboratory of the New Carlsberg Brewery in Copenhagen, Denmark. Claussen introduced the term “Brettanomyces,” meaning “the British yeast,” for this microbe at a special meeting of the Institute of Brewing in April 1904 and referred to its flavor as giving beer an “English character.” Since then, the British Brettanomyces strain has been known as Brettanomyces clausenii, the stronger Belgian strain as Brettanomyces bruxellensis, and the strain found in many lambics as Brettanomyces lambicus. Admiring mentions of “stale” porter seem to indicate that Brettanomyces, lactic bacteria, or both were partially responsible for the flavors of the best regarded porters of the 1800s.

As brewing techniques improved dramatically during the Industrial Revolution in England in the 19th century, so did the porter. When Daniel Wheeler introduced black “patent” malt in 1817, the makeup of most commercial porters changed quickly and dramatically. Now porter could be brewed largely from pale malt, with the new black malt as the flavoring and coloring. Pale malt could easily give more than 30% more extract than did scorched brown malts. During various periods British breweries paid taxes on the amount of malt used, and therefore the new efficiencies translated very directly to profits for brewers. Porter was often parti-gyled with stronger beers, increasing efficiencies even further. See parti-gyle.

Technological advances gave brewers many more choices. Some porters were brewed stronger, either for home or for export. These particularly rich beers were referred to as “stout porters,” and it is generally accepted that the most full-bodied and stout porters served as the genesis of stout as a somewhat separate beer style. By the early 20th century, stouts were seen as a different article, as evidenced by Samuel Sadtler, writing in A Hand-book of Industrial Organic Chemistry: “‘Porter’ has now come to mean a dark malt liquor, made partly from brown or black malt, the caramel in which gives it the sweetness and syrupy appearance, and containing four or five per cent of alcohol. Stout is a stronger porter, with larger amount of dissolved solids, and containing six or seven per cent of alcohol.” See stouts.

For the Baltic trade, a stronger version of porter, the Baltic porter, emerged. These porters are still made in many countries around the Baltic Sea, including in Finland, Sweden, and Estonia. In flavor, they may resemble less roasty imperial stouts and in strength they resemble barley wines, at 7% alcohol by volume (ABV) and above. They are clearly more sipping than quaffing beers and are usually cold fermented with lager yeasts. See baltic porter. Versions of porter were also popular in “East India” (India itself) and in “West India” (the Caribbean), and variants of these are today referred to as “foreign stouts.” These tend to be strong and to have at least a slight tang, an echo of the acidity that would have once been popular. In the days before refrigeration, the acidity would have prevented the beer from seeming overly sweet or malty. No doubt this quality still gives the beer better drinkability in very warm climates.

In Victorian England the porter also underwent a class differentiation, and some porter versions even climbed the social ladder to become favorites of the upper classes. One such was the “robust porter,” considered a beer for connoisseurs, not guzzlers. Strangely, this ale was favored more by well-heeled gentlemen than by genuine toiling porters; but considering porter’s rough working-class lineage, the term may, therefore, strike the careful linguist as a tautology and the sociologist as a peculiarity. Perhaps the key characteristic of a robust porter is its greater residual sweetness compared with the drier brown and Irish porters. It is also slightly higher in alcohol.

By the 1870s, however, porter’s reign was coming to an end. The practice of aging the beer had largely died away, the flavors had changed, and the breweries started to neglect porter. At one end of the flavor spectrum, pale ales were now the fashion in Britain; at the other end, stouts were taking over from porters. By the 1920s, most porters were shadows of their former selves—weak, thin, and not particularly palatable; porter was now considered a beer for old men. Whitbread’s great Chiswell Street Brewery brewed its last batch of porter on September 9, 1940, as air raid sirens pealed through the streets of London during the Battle of Britain. London brewers continued to produce porters into the 1950s, but by this time the style had largely faded into oblivion.

Only during the past few decades has the porter made a comeback of sorts, especially in North America, where the beer that once had a roughneck image is now a respectable, almost gentrified, craft beer style. Small British breweries have taken up the style somewhat more gingerly, but porter seems to be regaining steam there as well. Most contemporary craft brewers take porter to have more chocolate and coffeelike roasted flavor than do brown ales, but less of this character than stouts generally have. Most keep to a sessionable strength, or at least below 6% ABV, with many British versions coming in quite a bit lighter than that. Baltic porters, brewed stronger and cold fermented with lager yeasts, have also gained favor among American craft brewers. Some modern porters are even dry hopped, often with very un-English Pacific Northwest hop varieties, and such beers may be labeled as American porters; surely they are at least “Americanized.” See american hops, history and dry hopping.

Given that porter beer has seen so many changes over its nearly 3 centuries of existence, it is perhaps not surprising to see that it has arrived into the 21st century newly refreshed and ready for another star turn, this time as a foundation beer of the craft brewing movement.