Some of his early watercolours were continental scenes, probably based on prints, or on sketches by his father's friend, W.H.

[2] When his father left to take up a post teaching at King's College School in London, Cotman took over his practice as a drawing-master in Norwich.

Once the family home in St Martin's Plain in Norwich had been sold, however, he moved to London to assist his father, while his younger brother, John Joseph, who had accompanied his father to the capital, returned to take over the family's teaching practice.

[2] At first Cotman had no official post at the school, but in December 1836 he was appointed Assistant Drawing Master.

[5] John Sell Cotman thought his son had a "hard dry manner", although his style gradually loosened,[6] He was especially fond of painting shipping scenes, sometimes based on sketches made aboard a small boat owned by the Cotman family on trips along the coast to the Thames estuary and the River Medway.