Most famously, Eric used this Kazoo during the MTV Unplugged concert recorded on January 16, 1992. He played it on the song San Francisco Bay Blue and had it mounted on a harmonica rack.
As far as the exact model, unfortunately, kazoos are a bit of a mystery to the author of this page. From the looks of it, it looks just like a generic plastic kazoo with no branding visible whatsoever. If any kazoo experts stumble upon this page, be free to demystify the subject in the comments.
Two things. One thing related, maybe. EC purchased the Beano in late May, 1965, not ’66. That August, 1965 was the trip to Greece, returning Oct/Nov ’65.