Back to 633 Squadron, if you look carefully, the Bomb release switches they use are actually the transmit switch from an Army 38 mk3 Radio set.
Also, didn't the film makers buy the last Mosquitos from the RAF to use in the film?
Also, when Ron Goodwin wrote the music, he used 6 and 3 as inspriration. If you listen you can hear 6 beats followed by 3 slow beats in the beginning and through the music.