He was a brother of Joseph Hansom, creator of the Hansom Cab, patented in 1834, which was a low-slung cab, light enough to be pulled by one horse and carrying two or three passengers. It spread from London to other European cities and was the ancestor of the modern taxi.

In the 1840s and 1850s Charles Hansom was competing in the market for designing new Catholic churches in England with Augustus Welby Pugin, the greatest gothic revival architect of the day: Pugin did not find him agreeable.

For churches, Hansom preferred the architectural style called Decorated Gothic – one of his finest churches is St John’s in Bath (1863). In South Australia, however, Bishop Murphy had to cut costs and opted for the simpler Early English style. Hansom provided designs for some other Catholic churches in Australia. Archbishop Polding of Sydney and Bishop Goold in Melbourne bought various designs from him, in Decorated Gothic style, and used them for new churches in their fast-growing dioceses. Among them are the churches at Creswick, Kilmore and Port Fairy in Victoria and what are now the cathedrals at Bathurst and Ballarat.