Hum. Someone from the Beeb's pronunciation unit once said in an interview that if newsreaders had pronounced Khrushchev properly nobody would have recognized it.
I watched a 90s documentary about submarines the other day. The 1990s Americans all said SUBmaREENers and the Brits subMARiners; however, the Americans in a 1950s clip they included said subMARiners.
I wonder if somebody important mispronounced submariner and nobody dared correct him, so the new version stuck. I once read that the Thames rhymed with flames until George I got hold of it.