Copyright © 2004 the Brewery History Society

The origins of porter, and indeed its very name, are unclear and controversial as Martyn Cornell has demonstrated in his masterly article on the subject in the preceding issue of the BHS Journal¹. Cornell notes that first hand evidence as to porter's origins comes down to little more than a pseudonymous letter published in the London Chronicle in 1760². He debunks the many oft repeated embellishments on this source which have it that porter was ‘invented’ in 1722 at Ralph Harwood's Bell Brewhouse in Shoreditch to provide a more convenient form of ‘three threads’. This blended drink was a mix of three beers, often given as: fresh brown beer (mild), matured pale ale (twopenny) and matured brown beer (stale). The story goes that Harwood's porter had the contemporary name ‘entire butt’ or just ‘entire’, because it was served as a single product from one cask rather than by the then practice of filling a glass from three separate casks containing different beers; a task which publicans found irksome.

As Cornell demonstrates, in reality porter's origins are more complex than the mere result of a move to lighten the potman's workload. Cornell comes down on the side of those who favour the explanation that the word entire comes from mixing of wort from separate mashes prior to fermentation rather because the beer came from a single cask. He discounts the view held by some³, that porter and entire were originally different beers. He disputes the popularity of three threads and doubts that porter was deliberately produced to replace it. Rather Cornell suggests that porter may have arisen from a batch of accidentally over-kilned malt used by a mean or impoverished brewer who bought it cheaply. The dark brown beer that resulted was an unexpected success and its production spread. An alternative scenario presented by Cornell is that porter evolved around 1720 as an improved ‘hoppier, more aged interpretation of London brown beer, matured in butts, brewed using an entire mash, which caught on with the portering classes’¹. It is this latter scenario which I would like to develop a little further than Cornell has done, as it seems to me to fit most closely with both the historical and technical brewing data available to us. A scholarly "reconstruction from the fragments of contemporary testimony" by O MacDonagh⁴ makes a persuasive case for the origins of porter lying in the reaction of London brewers to increased taxation on malt and the relative cheapness of hops as the eighteenth century dawned. H.S. Corran ⁵ builds on this and links the emergence of porter with the earlier tradition of brewing strong ‘October’ beers. Whilst these are important factors, to properly understand the appeal of entire butt/porter to both drinkers and brewers it is necessary to link the strategies of beer production in the early 18th century and the biochemistry and microbiology of the processes.

The practice at the time was for strong ales to be stored for many months in wooden casks or vats before consumption. It may now be recognised that storage in this way would promote secondary fermentation by strains of the alcohol tolerant yeast genus Brettanomyces and lead to the production of very high levels of fatty acids and their ethyl esters^{6, 7}. It was this extreme ester level – perhaps as much as ten times taste threshold – rather than just the level of alcohol, which gave the narcotic effect characteristic of matured English ales right up to the end of the 19th century⁸. In a similar manner to strong ales, some brown beers were also matured. But the lower alcohol content of the latter encouraged the growth of other organisms in addition to Brettanomyces and these beers developed a distinctly tart acidity in addition to an estery fullness. Matured brown beer, ‘stale’, was a component of three threads and according to Obadiah Poundage² "many used all stale at fourpence per pot". The latter one feels must have been something of an acquired taste – anyone who has experienced Belgian lambic or gueuze will know what I mean. A third type of matured beer arose accidentally when, prompted by the relative cheapness of hops and increased tax on malt in the early 18th century, London brewers experimented with higher hop rates in their beers and ended up with what became known as porter. The breakthrough with porter was the discovery that a beer – even one made with cheap brown malt and significantly weaker than a strong ale – when brewed using a high enough level of hops became much less tart during storage than was usual for matured brown beer. Porter did however still develop the vinous, heavy, narcotic aroma and flavour associated with expensive strong ales. We can deduce that this is what happened, because we now know that the high hop rate would have kept the lactic acid bacteria at bay through the antibacterial properties of hop bitter acids⁹, but would have no affect on yeasts such as Brettanomyces. Hence Obadiah's observation² that porter " …well brewed, kept its proper time, became racy and mellow, that is, neither new nor stale… ". The Oxford English Dictionary defines racy in this context as ‘having a characteristic (usually desirable) quality, especially in a high degree’. In more modern brewers' parlance, porter ‘drank above its gravity’ because of its ester content. The combination of relative cheapness and desirable flavour made porter irresistible to the urban labouring classes; a taste eagerly exploited by what were to become the behemoths of the brewing industry.

Even its dark brown colour, typical of London brewed beers, was to its advantage as it disguised any deterioration in clarity with age. This robustness and cheapness made it suitable for mass production and amenable to distribution far and wide. As sales took off the need for long storage, often for a year or more, prompted the use of large vessels. Three thousand barrel capacity and greater storage vats eventually became commonplace ¹⁰ and porter brewers could undercut on price their ale brewing competitors who had none of the economies of scale or ability to use cheap materials in their more delicate products. Porter was an entirely new beer which to an extent mimicked the attributes of mixed beers but also delivered an enhanced mellowness. It came in a convenient single serving, from one wort and at a competitive price. Thus everybody was happy, the publican, the brewer and the drinker. No wonder porter was a success.

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