From 1959 onward, Janson was active in German film and television, culminating in a principal role on the circus drama Salto mortale (as Sascha Dorian). A spate of English-language projects followed, mostly war or escape movies like You Can't Win 'Em All, The McKenzie Break, and Murphy's War (with Peter O'Toole). He also guest starred on Upstairs, Downstairs as the dashing Baron Klaus von Rimmer.