Cossham began his involvement in the coal industry in 1845 at
Yate colliery. In 1848 he married Elizabeth Wethered and through a partnership with her family, began
Parkfield Colliery at Pucklechurch in 1851. As a caring employer, Cossham also built houses and a school for his colliery workers at Parkfield. The partnership opened several other coal pits, initially under the name of Cossham and Wethered Ltd and from 1867, the Kingswood Coal and Iron Company Ltd. The business came under control of Handel Cossham and Charles S. Wills after 1879 when the Kingswood and Parkfield Colliery Company Ltd was formed. In 1862, Handel Cossham built the British School in Thornbury, which remains today. The Cossham Hall, which was built as a
Wesleyan chapel, was purchased and donated to Thornbury by Cossham in 1888. ==Political life==