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."