The last time I watched this movie, it suddenly occurred to me that its climax can be best explained in Freudian terms. Perhaps the power of these underlying sexual connotations, along with the unforgettable music, is the reason why this part of the movie -- despite its Airfix special effects -- is so impressive.
The lead-up -- the usual subplots about love in wartime and angst over the possibility of making the ultimate sacrifice-- is mediocre to say the least, but once the squadron skims off across the North Sea to destroy Hitler's heavy water producing plant in Norway, you can't help getting swept along.
Those familiar with the basic concepts of Freudianism will observe that to get to the target they have to fly up a fjiord -- a deep, wet inlet with obvious feminine connotations -- and, once they get there, they have to franticly 'fumble around,' bombing a mountain until they hit the equivalent of a seismic G-spot. When this is done the 'earth' truly moves as an avalanche of rock thunders down on the Nazis. The only thing to do for the few survivors is return to base and have that post-coital cigarette!