William Callcott Knell was thought to have been the son of William Adolphus Knell. He lived with his father in Kentish Town, London. Callcott Knell was also the pupil of his father, and they painted alongside each other.

Between 1848 and 1865 he exhibited 17 pictures at leading London venues, including three at the Royal Academy, three at the British Institute and nine at the Royal Society of British Artists.

Of his exhibits, many were shipping scenes at sunrise or sunset. Like his father, Callcott Knell was obviously influenced by the Dutch tradition; from 1860 onwards, his style became looser, though still retaining its Dutch influence.