Lewis' travels to Spain and the Near East, including a long residence in Cairo, provided the main material for his long career. He 'resided so long abroad that at one time, though a member of the Royal Academy, he was for fourteen years absent from England, and adopted Eastern habits and costume, so that on his return he was called "Turkish Lewis."' (Art and Life in Turkey, Whitechapel Art Gallery, 1908, p 37)

As a watercolourist, Lewis added a robust note to his otherwise delicate and undramatic works through the liberal application of opaque body colour. This continued to be an essential feature of his art until he largely gave up watercolour for oil painting in 1858.