Although Royal's "Prince" model name is commonly associated with their hand vacs, this same model name was also used on some of their top-tier metal uprights starting in 1986.
One example is this model 786, dated September 1988.
Royal also made vacuums in the "Prince II" guise, with the same baby-blue trim color as the model 880.
This is a model 870 dated November 1986.
But, one question comes to mind: didn't Royal also reserve the "Prince" and "Prince II" names for such former Electro-Hygiene models as 285 and 903, and the trio of removable-head models 888, 980 and 990?
Ben, I have never seen any of the removable models with the word "Prince" on the bag. I believe all of them had Prestige or Supreme on their bags. The 990 was Galaxie prestige, the 980 was Supreme Electro Hygiene and the 888 was Royal Prestige.
I'd love to see a late 1986/early 1987 model 888, 980 or 990 sometime. It's those models whose serial # started with date code "I86" (9/1986) to "C87" (3/1987).