‘Marriage from love, like vinegar from wine – a sad, sour, sober beverage.’

This view, expressed by Lord Byron in his epic poem Don Juan, probably reflects the attitude of many to vinegar (though not necessarily, I hasten to add, to marriage). Vinegar is seen as a rather prosaic product sloshed with abandon onto chips until the vapours make your eyes water. Well, in this they would be wrong. For a start, the material used in chip shops is generally not vinegar at all but a product known in the UK as non-brewed condiment (NBC) – essentially glacial acetic (ethanoic) acid diluted down to around 5% (w/v), with caramel added for colour. Vinegar, on the other hand, is the product of two sequential microbial processes: the familiar anaerobic, alcoholic fermentation of sugars by yeast, followed by a second aerobic stage in which Gram-negative bacteria, mostly of the genera Acetobacter and Gluconacetobacter, oxidise the ethanol to ethanoic acid. To establish this point and protect their market, UK vinegar brewers in the 1950s took the NBC manufacturers to the highest courts in the land to prevent them from describing their product as ‘vinegar’ or even ‘artificial vinegar’. As a result, anything described as ‘vinegar’ must be the product of a double fermentation and, to this day, the less appealingly named ‘non-brewed condiment’ languishes mainly in chip shops.  

The vinegar brewing process is very robust since the potent antimicrobial activity of ethanoic acid ensures that not much else can survive during acetification. In most regions, the source of vinegar is generally the same as that of the local alcoholic beverage, for example, wine, beer (malt), cider, rice wine or palm sap. As a consequence, vinegar brewing is clearly a very ancient craft; whatever distant date in antiquity authorities give for the origin of winemaking and brewing (typically several thousand years BCE), it is a pretty safe bet to say that vinegar brewers discovered their vocation about 48 hours later when the first alcoholic brews soured. 
Vinegar has long played an important role in the flavouring and preservation of food, particularly before there was ready access to technologies such as canning, chilling and freezing, and in a large urban centre such as London its production was a significant industry. The sites of vinegar breweries are scattered all over London but particularly in the area just south of the river in the old county of Surrey, which was a national centre for the whole of the British Isles. Many have left no obvious trace. Potts’ vinegar factory once adjoined the Anchor (Porter) Brewery at Southwark but the site was gradually nibbled away in the course of developments during the 19th century, finally disappearing in 1911. A substantial vinegar works in Cuper’s Gardens was buried under the southern approach road to the Strand (now Waterloo) Bridge, which was opened in 1817. Slightly further afield, Champions Vinegar works stood for many years at the junction of Old Street and the City Road, an area now better known as Silicon Roundabout, an important hub in the new digital age (so they tell me). Elsewhere though, some remnants have at least partially survived, courtesy of the modern practice of converting industrial buildings into luxury living spaces. 
If you were to stand on the railway tracks southwest of Vauxhall Station and look south, possibly the last thing you would see (apart from perhaps a rapidly approaching train) is the clock turret of what was once Beaufoy’s vinegar brewery. The site can be viewed in greater safety from South Lambeth Road. The older buildings survive as part of a gated community, which boasts a private swimming pool and gym; the less-distinguished office accommodation has been converted into a ‘budget’ hotel. When it finally closed in the 1980s, the site was serving as a bottling plant for the Sarson’s brewery in Tower Bridge Road about 3 miles away. 
According to a manuscript in London’s Metropolitan Archives written in 1942 by Henry Sarson, the Sarsons started out as drysalters and are recorded as producing vinegar on premises close to the Champions works in City Road in 1831. There is an unsubstantiated story that John Sarson had provided haulage for Champions but when he lost their business he set up nearby as a rival. Initially, Sarson’s were making ‘wood vinegar’, essentially the non-brewed product, later buying in brewed malt vinegar from a company in Worcester before finally brewing their own. 
Sarson’s eventually moved to Tower Bridge Road in Bermondsey, taking over premises founded by the splendidly Dickensian-named Noah Slee in 1814. They continued producing malt vinegar, wine vinegar and distilled vinegar there until 1992, using what is known as the ‘Quick Vinegar Process’, where acetification of the alcoholic feed is achieved by trickling it over a bed of wood wool in a false-bottomed vat. Acetic acid bacteria, adsorbed onto the wood as a biofilm, oxidise the ethanol to ethanoic acid. The acetifying liquid collects in a sump at the bottom of the vat, from where it is recirculated until the desired level of acidity is reached. In early versions of this process, the bacteria were oxygenated by convection currents of air drawn up through the bed by the heat generated within it. It sounds quaintly archaic but in fact in its later manifestations, air supply, liquid flow rates and temperature were all carefully monitored and controlled. Conversion efficiencies in excess of 90% were routinely achieved and companies seeking to sell more sophisticated submerged culture equipment had to admit that they could not better the efficiencies obtained at Tower Bridge Road. 
Following closure, the site was transformed into flats known, somewhat erroneously, as The Maltings. Those puzzled by this change of use need only reflect that a two-bedroom flat in the Maltings was selling recently for £750,000, a sum that would buy you well in excess of a quarter of a million litres of vinegar (retail).