In the minute books of the London gas industry between 1820 and 1850 the name that stands out as the pre-eminent tar purchaser is Cassell. The volume of his purchases makes him a far from typical customer. Cassell's activities over thirty years provide a picture of how a tar distiller was able to use what he bought from the local gas industry.
Cassell's business was to buy gas works tar, to distil it and sell the product ‑an activity in which the gas companies themselves had failed. Despite some apparent problems Cassell, and at least one son, managed to survive in the business for many years.
There was, as we will see, more than one Mr. Cassell. They were based in Millwall where their name appears for several sites in the All Saints, Poplar, rate books from the 1830s.
In 1815, John Henry Cassell, probably the company originator, had a business in Poplar High Street where he made rainwater pipes and gutters. He then seems to have set up tar distillery in Millwall and is first noted in the gas company minute books when he bought tar from Imperial Gas Company in 1823. On that occasion he agreed to take all Imperials’s surplus tar, supplying the casks in which it would be transferred onto barges. This implies that he had access to a wharf somewhere on the river - something not available at Poplar High Street - as well as enough capital to fund purchase of the tar. At around the same time he was concluding a very similar deal with the South London Gas Company and another with the Chartered. He also appeared to have a partner, a Mr. Morgan.
Cassell seems to have pioneered the use of gas works coal tar as an ingredient of building materials ‑something that might give a clue to the identity of Mr. Morgan. In the 1820s a F.D. Morgan was in partnership with James Grellier on what was to become the site of the Millwall Atlas Chemical Works. On this site, very near to where Cassell was to set up his 'Lava Stone' works, Grellier and Morgan made Roman cement.This identification of Morgan is, however, very speculative.