One aspect they didn't cover, unless I missed it, was the method used on
the actual raid to ensure they flew at the correct height.
I think the story goes that they were scratching their heads trying to
figure out how they could make sure they were flying at the correct very
low height over water at night. Someone (Guy Gibson? Barnes Wallis? )
happened to go to a stage show and was struck by an idea when he saw the
spotlights on the stage. So what they ended up doing was rigging two
spotlights on the Lancasters so they converged when the aircraft was at
the correct height.
I understand it worked really well but you'd think it must have made the
aircraft even easier to air at for the defenders.
Mike