Just found Jacques Cousteau's film "The Silent World" 1956 on youtube there is a pretty good shot of an M20 at about 40:40, this was about 15 years after the sinking, there are rumours that Jacques recovered an M20 I wonder where it went?
I think they did bring an M20 upon to the deck of the "Calypso" in 1955,there is a photo in one of the several books released at the time of the TV series.