Derby was a water colour and miniature painter, born in Birmingham in 1786. He studied under the landscape painter, Joseph Barber, who taught him drawing. In 1808, he began to paint portraits in oil and water colour and also miniatures, after settling in London. He also made water colour copies of works he had seen by other artists and in 1825, he took over from William Hilton as the copier of images for Edmund Lodge's Portraits of Illustrious Personages of Great Britain, which he completed in 1834.
Between 1811 and 1837 Derby exhibited over forty nine paintings at the Royal Academy and at the Society of British Arts.
William Derby was also commissioned to paint the Earl of Derby in 1837, and later to produce a series of water colour drawings of the Earl’s ancestors’ portraits, dating from the reign of Henry VIII.
1838 brought about a stroke and Derby was thus only able to continue his work by enlisting the aid of his son, Alfred Thomas Derby (1821 – 1873). Around this time he produced a work entitled, Return from the Highlands, which was a copy of Edwin Landseer’s painting of the same name. This is thought to be Derby’s most notable work of the time.
In 1847 Derby died at his home near Regent’s Park, London.