Rock or Cork elm is a distinct species that has a very limited range in North America. Does not grow here in Pennsyvania. It is mostly north and around the great lakes. Sounds alot like American Elm in size but grows one straight trunk with horizontal branches. I see sycamore and elm listed in UK websites. Not sure if everyone knows this, but the glaciers retreated slowly out of Europe after the last ice age. Europe with left with far less diversification of species than we see here in the America's. I think they make do with what they have. Most of the good wood that is harvested in Pennsylvania is being shipped to China.