20 minutes ago, blue_dolphin said:
Maybe it was to distinguish them from the edible-pod peas that we do NOT refer to as "mange-tout."
Yeah, I know. British English has always taken food names fron French rather than Spanish or Italian as is more usual in the Americas. Hence aubergines instead of eggplants, courgettes instead of zucchini, coriander rather than cilantro, rocket rather than arugula etc.