My apologies, the Betley window is (at best estimates) mid-16th, not 15th century.

Thanks for mentioning that May Day also had a revival in America, Q. I didn't realize that. (Was this also in the 19th century?)

I'm afraid your hypothetical college student wouldn't get too far with that thesis topic, though, unless the maypoles used in the American revival were somehow associated with roses.

Cheers, Hester