In the US an english muffin is a disc about 3/4-1" thick and about 3.5" in diameter, dusted with cornmeal, and it is pre-sliced. Some brands have lots of air bubbles on the inside, which the Thomas' company calls "nooks and crannies".
"credit for the phrase "English muffin" is often given to Samuel Bath Thomas, an English baker who emigrated to New York City and began producing his “muffins” around 1880. The Merriam-Webster dictionary, however, names the origin as 1902.
Muffins are a more bread-like version of the crumpet..."
I purchased Robertsons the other day at a Harris Teeter store, but I was not sure how much credibility it had as an Orange Marmalade. (you know, in the US, Foster's is supposed to be Australian for "beer") It does say Original English Thick Cut.