Crawshay Family (Hirwaun Ironworks)  
In 1818 was bought on behalf of the head of the Crawshay family, William 1. He left their management to his son, William 11, and bequeathed them along with Cyfarthfa to the latter upon his death in 1834. In 1831 William 11 devoted everyday management at Hirwaun to his own third son, Henry who subsequently married a Penderyn village girl named Eliza Harris to the annoyance of his father. Their first two daughters were christened in Nebo Chapel (Hirwaun).

Anthony Bacon of Cyfartha, who leased Hirwaun Ironworks, decided to manufacture heavy canon for the American War of Independence. However he was a Member of Parliament for Aylesbury, and the law forbade him making arms. He overcame this problem by producing them in the name of his partner, Francis Homfray. It was under this name that the finished product was taken bridle paths by mules and packhorses from Hirwaun to Cardiff.

Cast steel was produced in small quantities at Hirwaun Ironworks in 1890