Born in Seven Kings, Ilford, Essex, Maddern attended Mayfield Boys school and afterwards joined the Merchant Navy at the age of 15 and served in the Second World War from 1943 until 1946, when he was medically discharged.
From 1950 to the early 1990s, Maddern appeared in films and TV series, often portraying military types. He was usually cast as sergeants or corporals, as well as privates, seaman or airmen, played either straight or comically. He played minor roles in five Carry On films. Among his many TV roles were Private Gross in Denis Cannan's Captain Carvallo and old Lampwick's son-in-law in The Dick Emery Show. In 1963, he had a guest role on Perry Mason as jewel smuggler Gilbert Tyrell, in the episode "The Case of the Floating Stones."
Besides acting, Maddern ran a script printing Business, and in 1991 opened a public speaking school. A lifelong Conservative Party voter, he offered special rates to Conservative MPs and constituency workers.
In his later years, Maddern devoted much of his time to charitable work. He was married with four daughters. He died from a brain tumour in Hackney, London, in 1993, aged 65.
