The 1955 film is good entertainment, but in some details it's a bit off the mark. As has been said, the actors portraying most of the members of 617 Sqdn are too old - a good number of the aircrew were in their teens, and Guy Gibson at 24 was much, much younger than Richard Todd who portrayed him (quite accurately, though). I don't think Michael Redgrave got Barnes Wallis quite right - a bit too much of the nutty professor, whereas Wallis was nothing like that. The big problem with the film was that the Bouncing Bomb (officially a 'mine') was still on the secret list, unbelieveably, and the film-makers weren't allowed to show it accurately. The official footage of test-drops included in the film had the bomb blacked out. One rather odd little detail - right at the end of the film Wallis catches up with Gibson to express his horror at the number of aircrew dead or missing, and while they're talking, way out in the background, a black dog can be seen trotting....plenty of superstitious people claim that this is the 'ghost of Nigger', Gibson's black Labrador dog, which is supposed to this day to haunt RAF Scampton. This scene was actually shot at Scampton. Weird.
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