Arthur Wakefield Horner was born in Melbourne, Australia on 10 May 1916, the son of Arthur Horner, a civil servant. In his teens he moved to Sydney with his family, where he began writing and acting in radio plays, and drawing cartoons for the Sydney Bulletin. He became a staff artist on Smith's Weekly and ABC Weekly.
He served in the army during the Second World War, commanding a camouflage unit in New Guinea and leading a Military History Field Unit in Borneo. He moved to London in 1947, where he studied at the Central School of Arts and Crafts. He drew cartoons for Lilliput and The Leader and became political cartoonist for Tribune. He married a fellow Australia cartoonist, Victoria Cowdroy, in 1948.
In 1950 he got a regular pocket cartoon slot, "Horner's Corner", for the News Chronicle, where in 1952 he created a daily strip, Colonel Pewter. He was also the paper's political cartoonist from 1954. After the News Chronicle merged into the Daily Mail in 1960, Colonel Pewter ran there until 1963, and then The Guardian from 1964 until 1970, when he created a new strip, The Thoughts of Citizen Doe, which ran for another two years.
He drew political cartoons for the New Statesmanfrom 1966 to 1972, and also contributed cartoons to the Times Education Supplement, The Humanist, The Sun, Private Eye, Punch, Truth, the Sunday Times, and TV shows on the BBC. He returned to Melbourne in 1976, and revived Colonel Pewter for the Melbourne Age, where it had previously been syndicated, for a brief period in 1977. He also drew another strip, Archangel Uriel, political cartoons and theatre caricatures for the same paper.
He was also a printmaker, making lithographs, etchings, aquatints and seriographs, and an animator. He retired after the onset of Parkinson's Disease, and died in Melbourne on 25 January 1997.