Johnny Johnson, a bomb aimer on the Dambusters raid of 16 and 17 May 1943, tells us about the one complete bouncing bomb that got into the hands of the Germans.
"[Bob] Barlow had flown into electric cables and crashed into the next field but as he did so his bomb came off and it didn't explode," says Johnny. "The only reason I could think for that was that at that stage the bomb aimer hadn't fused his bombs."
Johnny went on to explain how bomb fusing worked and his theory behind the unexploded bomb.
"The bombs are fused from the bomb aimer's compartment. Bombing fuses, when switched on, set out the fuses ready to explode when the bomb was dropped. In normal bombing practice that was done as soon as you'd crossed the English coast but on this occasion I think it was left to the individuals at whatever time they felt it was appropriate and that’s the only reason why I can think they didn't explode."
"What it did mean, of course, was the Germans had a perfect copy and they worked on this. I suppose, fortunately for us, Hitler was more concerned about his V1-V2 sites than the bouncing bomb."
Hitler's V1 flying bombs, capable of a 400-600m blast radius, and infamous V2 'vengeance' rockets, the world's first ballistic missiles that landed at a shattering 3000 miles per hour, were responsible for some of Hitler’s most devastating attacks on London and Britain.
"It created quite a lot of apprehension over here where it was anticipated that the Germans would make reprisal attacks and so the dams over here were fortified much more strongly, just in case."