In looking deeper I find:
There is a confusion of species here. Two??? They range at least most of the east coast of the Americas. Most common in the "North Atlantic", (circumpolar???) So for sure in England. The salinity preference is ten PPT and up, so ,again, yes in England. Add to that the fact that as natural beds in various countries became depleted, OYSTERS WERE COMMONLY TRANSPLANTED from one area to another, one country to another. See Mark Kerlansky,'The Big Oyster'. Blue points, so prized by NY and Conn., we're originally from the Chesapeake, once the oysters in this area depleted to near exterpation, spat and shell base were dredged and hauled north to replace them. Try telling that to some people. I now have a seafood house and an oysterman friend on the lookout. And some recipes. Where I am from, Annapolis, oysters WERE a way of life.
Hope you found this informative. New subject for me, I'll share as I learn.
Bill