Alan Lyle-Smythe was born in Surrey, England. Prior to World War II, he served with the Palestine Police from 1936 to 1939 and learned the Arabic language. He was awarded an MBE in June 1938. He married Aliza Sverdova in 1939, then studied acting from 1939–1941.

In January 1940, Lyle-Smythe was commissioned in the Royal Army Service Corps. Due to his linguistic skills, he transferred to the Intelligence Corps and served in the Western Desert, in which he used the surname “Caillou” (the French word for ‘pebble’) as an alias.

He was captured in North Africa, imprisoned and threatened with execution in Italy, then escaped to join the British forces at Salerno. He was then posted to serve with the partisans in Yugoslavia. He wrote about his experiences in the book The World is Six Feet Square (1954). He was promoted to captain and awarded the Military Cross in 1944.

He wrote his first novel, Rogue’s Gambit, in 1955, first using the name Caillou, one of his aliases from the war. Moving from Vancouver to Hollywood, he made an appearance as a contestant on the 23 January 1958 edition of You Bet Your Life.

Several of Caillou’s novels were filmed, such as Rampage with Robert Mitchum in 1963, based on his big game hunting knowledge; Assault on Agathon (with Nico Minardos as Cabot Cain), for which Caillou did the screenplay as well; and The Cheetahs, filmed in 1989.

He appeared as an actor and/or worked as a screenwriter in such shows as Daktari, The Man From U.N.C.L.E. (including the screenwriting for “The Bow-Wow Affair” from 1965), Thriller, Daniel Boone, Quark, Centennial, and How the West Was Won. In 1966, he had a recurring role in NBC’s “Tarzan” TV series starring Ron Ely. Caillou appeared in such television movies as Sole Survivor (1970), The Hound of the Baskervilles (1972, as Inspector Lestrade), and Goliath Awaits (1981). His cinema film credits included roles in Five Weeks in a Balloon (1962), Clarence, the Cross-Eyed Lion (1965), The Rare Breed (1966), The Devil’s Brigade (1968), Hellfighters (1968), Everything You Always Wanted to Know About Sex* (*But Were Afraid to Ask) (1972), Herbie Goes to Monte Carlo (1977), Beyond Evil (1980), The Sword and the Sorcerer (1982) and The Ice Pirates (1984).