Rowland V. Lee presented the idea to Universal Pictures and The Hollywood Reporter announced in June 1939 that production was in plans to start. The studio gave the film a $500,000 budget with a 36-day shooting schedule that started on August 11. Trade papers stated on July 27 that Brian Donlevy was being tested for the lead role of Richard III with George Sanders being signed to the role one week later. Neither casting turned out when Lee approached Basil Rathbone for the role. Rathbone had previously worked with Lee on The Sun Never Sets and Love from a Stranger. Rathbone was pre-occupied by filming Rio at the time but was able to split his time between both productions during the first week of production. The role of Mord the Executioner was made for Boris Karloff who had signed on to the studio for two additional features after Son of Frankenstein. Initially, his character was to have a full black beard but this concept was removed in favour of a nearly hairless look. Filming Art director Jack Otterson developed a recreation of the tower in the studios backlot which involved consulting historical records and original blueprints of the 13th century building. The completed structure stood at 75 feet high and would later be re-used in other Universal Studios productions. The staging of historic battles at Bosworth and Tewkesbury lead to a call for over 300 extras on August 19 and required the production to travel 20 miles north of Hollywood to a ranch in Tarzana. Strong winds caused problems with the fog machines used, making it impossible to film. Lee had the crew move on to film the Battle of Tewkesbury scenes, which involved rain machines that made the extras' cardboard helmets fall apart. The assistant director of the film stated in his film diary that "a group of unruly, uncoooperative and destructive extras dressed in helmets and armor made this one of the most unsuccessful days the studio had with a large crowd of people in many year". Lee attempted to shoot battle footage again on August 22 and tried to film small groups of actors against process plates of previously shot battle scenes. As Lee's last two films for Universal exceeded their original budget, pressure was placed on Lee to cut some costs on Tower of London. Universal told Lee to remove the child marriage scene, which Lee