Good point CollegeFlyer. So, to clarify, on EI:
Premier is the title for Business Class. It seems that 'Business Class' is being used more commonly by EI these days with the 'Premier' brand being renamed 'Business'.
EI do not have economy plus seating or any kind of 'premier/premium-economy' seating.
Oh! I didn't think your post was going to cause the confusion, but that EI's own branding (and sharing a term which UA uses to refer to something different) was going to cause the confusion. But good clarification. (Maybe EI or UA should publish a clarification too, so that people who aren't on FT will see it. FTers are probably more likely to know the difference to begin with.)