Thanks, Patrick, cool video! I couldn't get it to work from your blogspot, but went to British Pathe and viewed it. The metal frames are the kind of thing I was talking about when I attempted to explain that different-sized open areas would result in different-sized bubbles ("...a glass object blown into a metal structure that become part of the finished piece."). In the objects in the video, though, the glass would be of a fairly similar thickness throughout the piece, or thinner where openings were bigger, as others have pointed out. The big mystery behind the bosses on the Steuben and Hawkes pieces is how they ended up a lot thicker than the rest (which I'm convinced they are).
Haven't heard back from the guy with the vase. After Easter if I haven't heard anything I'll pester him again.
Cathy, I never made it to Canberra. I've heard it's a very nice city, though!