From: Westminster City Archives
Image via: theabcsoftea.com
The later part of the 19th Century seems to have held, in some quarters, a certain distrust of yeast, with its associations to the 'demon drink' and newly-discovered sickness microbes. This prompted the development of 'Non-Brewed Condiment' as an alternative to vinegar, and may have been the inspiration for Aerated Bread.
The process was developed by Dr. John Dauglish who established the The Aerated Bread Company Ltd in 1862 in Islington in London. It grew to have 150 branch shops and 250 tea rooms. The 'ABC' became an important feature of Victorian and early 20th Century city life, it is frequently mentioned in literature and credited with providing the convenient neutral ground on which the Suffragettes, among others, were able to flourish.
The firm was taken over by Allied Bakeries Ltd in 1955 which became in turn a subsidiary of Associated British Foods Ltd. It ceased trading in the early 1980's.
An Aerated Bread Shop, from 'Highways and Byways in London', 1920
'On the Healthy Manufacture of Bread: A Memoir on the System of Dr. Dauglish' (1884)
https://archive.org/details/onhealthymanufa00dauggoog