Lennox Frederick Wenn was born in Tulse Hill, London, on 27 November 1918, son of Frederick Hugh Wenn and his wife Dorothy, née Hill. His father, who was manager at sports outfitters George Grose, was responsible for press advertising and placed regular ads with the Amalgamated Press, who in return supplied him with complementary copies of AP comics and story papers. Len's favourites growing up were The Magnet and The Gem.
He left school at 14 and joined the AP as an office boy. Two years later he approached editor Harold Garrish about working in comics. Initially he worked as office boy to Len Stroud, editor of The Butterfly, and later for Bill Fisher on the Tiger Tim line of titles. He became the regular writer of the Bruin Boys prose story in Tiger Tim's Weekly.
He enlisted in the army in 1939, serving in Africa and Italy, and working on forces newspapers The Union Jack and The Crusader. He returned to the AP after demobilisation in 1946, staying with the Tiger Tim group until 1954 when he was appointed editor of Jack and Jill. He also edited Sun, The Comet, Schoolgirls' Picture Library and Dick Turpin Library, and launched the popular girls' weekly Sally in 1969. From 1971 to 1981 he was editor of Buster.
Throughout his career he wrote scripts for various titles, including the ones he was employed on. Stories he wrote include "Go On, Hate Me!" (1976-77) and "The Birds" (1978) for Jinty, both drawn by Keith Robson.
In 1981 he retired to Kent, where he died in the second quarter of 2003.