Howard's World War II activities included acting and filmmaking. He was active in anti-German propaganda and shoring up support for the Allies—two years after his death the British Film Yearbook described Howard's work as "one of the most valuable facets of British propaganda". He was rumoured to have been involved with British or Allied Intelligence, sparking conspiracy theories regarding his death in 1943 when the Luftwaffe shot down BOAC Flight 777 over the Atlantic (off the coast of Cedeira, A Coruña), on which he was a passenger.