William Albert Clark was born in Islington on 3 January 1880 to animal painter Albert Clark and his second wife Harriet Jane (nee Ireland). He is actually named Albert William on his birth certificate but was presumably known by his middle name to avoid confusion with his father.

Like his father and older half-brother Frederick Albert Clark, William specialised in portraits of horses, sometimes with their jockeys, or carriages and drivers. He also painted prize cattle and the occasional dog portrait. There is at least one version of "The Runaway Horse" (a painting originally created by his grandfather James Clark) attributed to William Albert Clark, named "Breaking Loose".
In 1900 the young William Albert Clark married Annie Louisa Sutton. The couple lived at Kelvin Road, Islington, and on the 1901 census William gives his occupation as "Animal Painter". By 1911 William and Annie had three daughters and had moved to 51 Hanover Road, Tottenham. From here he travelled widely to obtain commissions; his business card stated "Gentlemen waited upon in any part of the country".

His usual signature was W. A. Clark, and he sometimes added the letters RAS after his name, indicating that he was a member of the Royal Agricultural Society. The details of the animal depicted, such as its name, pedigree and prizes won, were often neatly printed on the front of the canvas.
Like his father and brother, William Albert Clark is not known to have exhibited with any of the major art societies. He continued to live at 51 Hanover Road until his death on 5 March 1963.

Source:
Website of The Clark Family of Artists, 2020