What might be the English name for this chilli?
This isn't a definitive answer, but I suspect that the name you have for it is the english name. There are many many varieties of chili and many of them are not found in the english speaking parts of the world, so the local name is the english name.

I googled the name as you provided it and found that it probably is called an unhelpful "green chili". It is very probable that the "morris" part is a corruption of "morich" which translates to pepper (see the entries for morich on this list of Bangladeshi spices). Within that list is an entry for "green chili pepper" which has the local name of "kancha morich" or "kancha lonka", which seems to be a variant name with associated recipes.

I have been unable to find a Scoville rating for this chili or even which of the species of Capsicum it is, but the rating is normally done on dried chili (I think!). There is an excellent summary of chili varieties and types in this page, which might give you some direction.