A memorable feature of the film is the tune that is whistled by the POWs—the first strain of the march "Colonel Bogey"—when they enter the camp. Gavin Young recounts meeting Donald Wise, a former prisoner of the Japanese who had worked on the Burma Railway. Young: "Donald, did anyone whistle "Colonel Bogey" ... as they did in the film?" Wise: "I never heard it in Thailand. We hadn't much breath left for whistling. But in Bangkok I was told that David Lean, the film's director, became mad at the extras who played the prisoners—us—because they couldn't march in time. Lean shouted at them, 'For God's sake, whistle a march to keep time to.' And a bloke called George Siegatz ... —an expert whistler—began to whistle "Colonel Bogey", and a hit was born."