Born 27 July 1875 at the Royal Naval Hospital, Stonehouse, Plymouth, only child of Staff-Surgeon Charles Lyon Ridout, RN, MRCS 1866, and Ada Perley Scott, his wife, daughter of Archibald Scott of Halifax, Nova Scotia. C L Ridout was at that time on the staff at Stonehouse and later served in HMS *Tourmaline* in the East Indies station and died of malarial fever in Mauritius. C A S Ridout was educated at Plymouth College and in 1887-94 at Sherborne School, where he played in the cricket XI and Rugby football XV. He received his medical training at St Bartholomew's Hospital, qualifying in 1899 and winning a Jeaffreson exhibition. After serving as clinical assistant in the throat department at Bart's, he was house surgeon at the North Staffordshire Infirmary at Stoke-on-Trent, and in 1904 became senior house surgeon at the Royal Portsmouth Hospital, becoming pathologist in 1906, and eventually senior surgeon at the Hospital and at the Portsmouth and Southern Counties Eye and Ear Hospital, where he had charge of the ear and throat department. He was also otolaryngologist to the Gosport War Memorial Hospital and laryngologist to the Midhurst Cottage Hospital. During the war he was commissioned major, RAMC on 22 August 1914, and served at the 5th Southern General Hospital, Portsmouth, at the 29th Stationary Hospital at Salonika 1916-17, and in Italy 1917-19. He was secretary of the Portsmouth division of the British Medical Association and president of the Southern branch, local general secretary for the Portsmouth meeting of the Association in 1923, and a vice-president of the section of laryngology and otology in 1924. At the Royal Society of Medicine he was president of the laryngological section in 1937-39. He organized two clinical meetings yearly among his colleagues at Portsmouth. In March 1939 he became chairman of the Portsmouth medical war committee, and carried through a scheme for the protection of the practices of colleagues called to national service. Ridout married on 11 July 1911 Gladys Mary Hooper, who survived him with three sons and five daughters. One son died before him; another played, like his father, in the Sherborne School XV, and served in the Army in Flanders and through Dunkirk in 1940; another son, Dudley Lyon Ridout, MRCS 1938, while serving as surgeon-lieutenant RNVR was present in the naval engagement at Narvik on the Norwegian coast in 1940; one daughter was a medical student at the time of her father's death. Ridout lived at St Elmo, Clarendon Road, Southsea. He died on 9 August 1941, and was buried at Sherborne after cremation at Southampton. A memorial service was held at Portsmouth Cathedral. He was a man of great physical powers, fond of motoring, fishing, and football. Publications: Aphonia and hoarseness. *Brit med J* 1929, 1, 393. The acute ear. *Proc Roy Soc Med* 1928-29, 22, 1292. Early or late operation in acute mastoiditis. *Ibid* 1932-33, 26, 733.