William Thompson was a partner with Richard Crawshay in a leading firm of iron merchants in the City of London.
After the Homfray family withdrew, William Forman became co-owner of the Penydarren Ironworks with William Thompson of London.
1799 After Crawshay's death, William Thompson formed a new merchant house with Samuel Homfray and William Forman - Thompson, Forman and Homfray
1799 William Thompson developed major interests in south Wales iron furnaces; he leased the Tintern Abbey Ironworks.
1800 Samuel Homfray leased coal and iron ore from the Tredegar estate and formed a partnership with Thompson and others to establish the Tredegar Iron Works with a capital of £30,000.
1801 Homfray was also involved in establishing the Aberdare Ironworks in 1801 and was a partner in the Penydarren Co at Merthyr Tudful (Merthyr Tydfil) where Thompson acquired an interest.
His nephew, William Thompson (1793-1854) joined the business of his uncle.
1806 The elder William Thompson purchased three-tenth shares of the Redbrook and Lydbrook Ironworks.
The younger William inherited his uncle's fortune.
Sources of Information
- Biography of the Formans, ODNB 
- Biography of William Thompson, ODNB