I am not sure who the actors are who provided live action reference scenes for the animators here. But I do know Milt Kahl animated this section of the film.
When asked about working on the two characters Milt said that they weren't too much fun, but that they worked ok for the story. The earlier introductory scenes of the King and Duke were animated by a different animator, and at that time Milt felt compelled to re-draw all of those scenes in order to improve the poses and overall draughtsmanship.
