A stage actor as a child in the '30s, Lydon began acting in films at the end of the decade and during the early '40s starred in Paramount's popular Henry Aldrich series. Lydon also appeared in supporting roles in such notable films of the '40s and '50s as Michael Curtiz' Life with Father, Victor Fleming's Joan of Arc, John Ford's When Willie Comes Marching Home, John Sturges' The Magnificent Yankee, and William A. Wellman's Island in the Sky. By the late '50s, Lydon shifted his energies to producing and directing for telelvision, but continued to play occasional small roles in films, including Death of a Gunfighter and Scandalous John.