In 1819, two former school friends, Thomas Blackwell and Edmund Crosse, were apprenticed to a firm making pickles and sauces at premises in King Street near present-day Shaftesbury Avenue.

They excelled to the extent that, 10 years later, they bought the business for £600 and the partnership, thereafter known as Crosse & Blackwell, came into being. 

Substantial expansion began in 1838 with the purchase of the former residence of Lady Cornelys at 21 Soho Square. Socially speaking, Soho was an area in relative decline as the wealthy minor gentry moved westwards, and craftsmen, manufacturers and tradesmen moved in to create a vibrant area of small businesses and domestic housing. In the 1850s, when the pioneering nurse Mary Seacole was moving into lodgings at 15 Soho Square, Crosse & Blackwell were acquiring and converting a number of surrounding buildings spreading between Soho Square and Crown Street (now Charing Cross Road). In nearby Little Denmark Street, a building and yard were bought for the production and warehousing of jams, fruit preserves and confectionery. They established a vinegar brewery off the Caledonian Road, installing one of the largest vats of the time, holding 115,000 gallons (more than half a million litres), to supply their ever-growing needs. Wharves in Millwall and Battersea were acquired for the transport of ingredients and products. 
In an era predating scientific understanding of microbial activity in food spoilage and foodborne illness, the company’s product range was based largely on traditional recipes and an empirical approach to shelf life and stability. Today, food microbiologists would describe the pickles, sauces and jams they produced as examples of the hurdle concept of food preservation, where combinations of suboptimal factors such as reduced water activity, low pH and weak organic acids inhibit microbial growth and spoilage. 
Understanding of the scientific basis of this approach came much later when the essential physiology of foodborne microorganisms was explored. Knowing how microorganisms respond to different environments allowed development of quantitative predictive models as practical tools for formulating safe and stable foods. This really began in the USA in the 1920s with Esty and Meyer’s mathematical treatment of microbial inactivation in canning, and has continued through to the current ComBase models describing both growth and inactivation under a variety of conditions. Along the way, formulas specifically predicting the composition of stable pickled products were also developed. The most elaborate of these, from the Unilever laboratories in the Netherlands, is known as the CIMSCEE code (the acronym deriving from the French title of the European Sauces Trade Association): 
15.75 (% undissociated ethanoic acid)+3.08 (% salt)+(% hexose)+0.5 (% disaccharide) =∑ 
In the equation, each term represents one of the principal antimicrobial factors and their relative contribution. These are simply added together to give a value, ∑. Readers may recall that in The Hitchhiker’s Guide to the Galaxy, the supercomputer ‘Deep Thought’ was asked the answer to the ‘Ultimate Question of Life, the Universe and Everything’. After 7½ million years, it came up with an answer: 42. Well, for pickle and condiment makers, who admittedly may have more limited horizons, the answer turns out to be 63. If, applying the CIMSCEE formula, ∑ exceeds 63 then a sauce will be microbiologically stable without refrigeration, even after opening. 
Relying on traditional empiricism, however, Crosse & Blackwell grew throughout the 19th century, supplying expanding urban markets and creating international brands. From the very beginning they were adept at promotion, obtaining a royal endorsement from Queen Victoria and employing celebrity cooks, starting with a former chef to Napoleon, Senor Qualiotti, who introduced several new products including, for Christmas 1832, ‘Piccalilli’. The company also diversified its range to reflect the influence of Empire with, for example, ‘Captain White’s Oriental Pickle’ and ‘Colonel Skinner’s Mango Relish’, and they acted as agents for Lea and Perrin’s ‘Worcestershire Sauce’ – another product inspired by the Indian subcontinent. With the celebrity chef Alexis Soyer, they ventured into French cuisine including inter alia the intriguingly named ‘Soyer’s Sauce for Ladies’. The relatively new technology of canning was not overlooked, with the acquisition of the Bermondsey canning company founded by Donkin, Hall and Gamble, a salmon cannery in Ireland and production of a variety of thermally processed potted meats. 
The problems of operating in central London eventually told and in 1921 the company began to move manufacturing away from Soho Square to a former machine-gun factory in Branston, near Burton upon Trent – a move that inspired another new product, ‘Branston Pickle’. In 1960, Crosse & Blackwell was acquired by Nestlé and is now owned by companies in Europe and the USA. The Branston brand is owned separately by a Japanese company. 
Following the company’s move to Branston, much of its existing property in the West End was sold off. A warehouse on Charing Cross Road was redeveloped, later becoming the site of the Astoria, a legendary music venue in the capital until its closure in 2009. Its subsequent demolition in the Crossrail redevelopment of Tottenham Court Road Station allowed Museum of London archaeologists the opportunity to conduct an excavation of the area, expertly described in a recent book. 
The excavation unearthed a cornucopia of food packaging from an era before plastics, including a variety of glazed earthenware and stoneware vessels, glass bottles and jars, lids and stoppers, as well as a few tin cans (fabricated locally in premises on Dean Street). Though many are quite decorative, sadly most will be relegated unseen to museum storerooms. Perhaps we should emulate Athens, where archaeological artefacts (admittedly older) are displayed at the local metro stations? I wait with bated breath for others to join me in a campaign to celebrate our illustrious pickling heritage more visibly. Bring out the Branston! 
Further reading 
Jeffries N, Blackmore L, Sorapure D. Crosse and Blackwell 1830–1921: a British food manufacturer in London’s West End. Museum of London Archaeology, 2016.