Stanley Clark was born in Stoke Newington, Hackney, to landscape artist Octavius Thomas Clark and his wife Ellen in 1888. He grew up in Islington and West Ham with his brother and three sisters. In 1910 Stanley married Edith Louisa Marina Warman and the couple moved to 37 Colchester Avenue, Manor Park. His occupation is given as "artist" on the 1911 census record. Stanley and Edith had two sons.
Stanley was taught to paint by Octavius. Like his father, Stanley is known for his pastoral landscapes, often with thatched cottages. There is also one auction record of a mountain scene which is similar to the work of his older brother Louis Edgar Clark. Stanley's paintings were produced mainly for the American market and were usually unsigned, as stipulated by his dealer's contract. His eldest son Ronald would deliver paintings to Stanley's buyer at the Strand Palace Hotel in London. According to Ronald, Stanley received 30 shillings a pair, 50 pairs at a time, and was paid cash on delivery. He did not exhibit with any of the major art galleries.
Later in life Stanley was employed as an electrical engineer's beltman. He died at his home, 8 Tollesbury Gardens, Ilford, Essex, on 20 May 1942. He was 54, the cause of death was heart failure due to rheumatic fever. Stanley left £152 17s 8d to his widow Edith.