I don't think I can really go along with the notion that corn = wheat in England. I've never seen any literary evidence of such a confusion.
Interestingly enough, there was certainly no confusion between wheat and Indian corn in the 1840s. During the Irish Famine (1844-1849) Ireland was still exporting bumper crops of wheat to England and other overseas markets while at the same time importing quantities of maize from the US to feed the starving Irish. Not enough of course, but more than your average laissez-faire government of the period actually wanted to provide from the public purse.
What little they did provide didn't do the Irish much good anyway. Without wanting to have a swipe at the Irish, they simply didn't know what to do with it, potatoes being the staple prior to the blight.
They tried boiling it, parching it, roasting it and even eating it raw. The average peasant family wouldn't have been able to grind it even if they had known that they should do so. Grinding stones weren't exactly thick on the ground, although at the time cyst nematode certainly was.
It caused a lot of illness, including perforated stomach linings because, as we all know today, maize is not broken down by the human gut without considerable pre-processing. And even where it didn't cause sickness it still didn't provide much nitrition because it wasn't digested properly.
