Roberts developed a highly personal style of portraiture. His earliest surviving drawings are predominantly portraits, and include a self-portrait of about 1911. Roberts preferred to employ familiar models and regularly used himself, his wife Sarah and his only son, John. The format increasingly favoured by the artist was head and shoulders. This allowed him to concentrate on the face and exclude any surrounding details which might be distracting. In 'Self Portrait Wearing a Cap' Roberts depicts himself in a shirt, wearing braces, tie and a flat cap. He thus identified himself as a working man, a persona he projected in later self-portraits of the 1950s and 1960s.