Alan Lyle-Smythe was born in England. Prior to World War II he served with the Palestine Police from 1936-1939 where he learned the Arabic language. Alan Caillou. He was awarded the Order of the British Empire in June 1938. Gazette Website: PDF NavigatorHe married Aliza Sverdova in 1939, then studied acting from 1939-1941. Authors "C" Of Ultimate Mystery Fiction Web Guide

In January 1940, Lyle-Smyth was commissioned in the Royal Army Service Corps. Due to his linguistic skills, he transferred to the Intelligence Corps Gazette Website: PDF Navigator and served in the Western Desert where he used the surname "Caillou" (the French word for 'Stone') 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 partisan 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. Gazette Website: PDF Navigator

Following the War he returned to the Palestine Police from 1946-1947 then served as a Police Commissioner in British occupied Italian Somaliland from 1947-1952 where he was recommissioned a Captain Gazette Website: PDF Navigator. He wrote of these years in the book Sheba Slept Here.

After work as a District Officer in Somalia and professional hunter, Lyle-Smith travelled to Canada where he worked as a hunter than became an actor on Canadian television.

He wrote his first novel Rogue's Gambit in 1955 first using the name of Caillou. Moving from Vancouver to Hollywood, he made many appearances as an actor as well as a screenwriter in such shows as Daktari, The Man From U.N.C.L.E., Thriller, and Quark where he played "The Head".

Caillou wrote a variety of paperback thrillers under his own name and a nom de plume of Alex Webb with such heroes as Cabot Cain, Colonel Matthew Tobin, Mike Benasque, Ian Quayle, and Josh Dekker as well as writing many magazine stories.

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 Manardos as Cabot Cain that Caillou did the screenplay as well, and The Cheetahs filmed in 1989.

He died in Sedona, Arizona, USA in 2006.