Around the end of the Napoleonic War, there was a rich gentleman on business in the West Country. As he was rich, he stayed in a nice hotel. He liked a snack for his supper if he arrived back from business late in the evening .
He particularly liked the local cheese known as Double Gloucester, which is a reddish coloured hard cheese. In the summer the colour in the cheese comes naturally from the amount of carotene in the cow’s diet. At other times — and this was a practice dating back to the middle ages — a natural food dye known as Anatto was added to Gloucester cheese to convince buyers they were getting the real thing and top quality cheese at that. This practice was copied by other dairies around the country which produced their own such as Red Leicester and Scottish coloured Cheddar.
The gent had eaten cheese on toast at home for years without any digestive problem. But that one night after the snack in his hotel he was beset with terrible abdominal pains. He recovered, but the next time he ate cheese at the hotel the same thing happened. The cheese was further implicated when a kitten was violently ill after eating a bit of rind cut from the cheese. The hotel — being posh — had ordered the cheese not from a local farm, but from a “respectable shop” in London. The gentleman inquired of the shop what might have been added to their cheese to make him feel so unwell. Yes, they conceded, they had added Anatto to the cheese, but they got this Anatto from their usual supplier with whom they had traded for years.
Further enquiries ensued. “Well maybe…” said the cheesemaker. Maybe the Anatto had been of “defective and inferior quality” and hadn’t produced an orange enough colour for our liking. So, yes, we did add a little vermillion to the mixture — but we got it from a reputable wholesale chemist.
Trouble was that they had not told the chemist that they were adding the vermillion to food. The chemist usually sold vermillion as a pigment for house paint. To boost the red colour in red paint he naughtily but routinely added the very poisonous red lead to his vermillion, certain that no-one would be so foolish as to eat paint.
So while most adulteration of food and drink was almost certainly deliberate in the 19th century, once in a while there was a chain of events, each link innocent in itself,which led to disaster. Nowadays chains of this nature leading to catastrophe are usually contained the text of air accident reports and the like.