late 1977. Shepperton Studios outside London were used for most indoor scenes and included a full-scale mock-up of a Lancaster bomber, while scenes were shot around the Đurđevića Tara Bridge, Montenegro, and Jablanica Dam on Jablaničko Lake in Jablanica, Bosnia and Herzegovina with the assistance of Jadran Film. Scale models of the dam, the valley and the bridge were constructed at the Mediterranean Film Studios in Malta. President Tito of Yugoslavia authorised his government to assist the production, including providing 2,000 soldiers as extras as well as uniforms and equipment and several Yugoslavian army T-34 tanks. He visited the set. Some scenes were also shot in the Royal Naval Dockyard (South Yard) in Devonport, Plymouth. During a shot of the railway carriages the letters PSTO(N) can be seen, this stands for Principal Supply and Transport Officer (Navy), and on Jersey in the Channel Islands. George MacDonald Fraser was hired to do further work on the script during filming in Yugoslavia, in part because he and Guy Hamilton got along well when both worked on Superman (1978). However Fraser is not credited on the film. Edward Fox said five people worked on the script. "The action had been laid down but the characters were still stick figures. We had to dress them up and make the lines fit them as we went along." Ford said during filming, "I was lost because I didn't know what the story was about. I didn't have anything to act. There was no reason for my character being there. I had no part of the story that was important to tell. I had a hard time taking the stage with the bull that I was supposed to be doing." The bridge over the Tara River, which is the target of the commando operation in the film, was destroyed by partisans in 1942 with the original engineer that built the bridge (Lazar Jauković) involved in the operation to destroy it. Shaw said during filming that "I'm seriously thinking that this might be my last film... I no longer have anything real to say. I'm appalled at some of the lines... I'm not at ease in film. I can't remember the last film I enjoyed making." Shaw's words proved prophetic as he died in August 1978 of a heart attack, before Navarone was released. It was his penultimate film, as he was filming Avalanche Express when he died.