I was rumaging in Rye, Sussex, this morning, and was reminded of this thread when I saw a glass bowler/top hat, which seemed cheap at £3., so I invested heavily in what I'm hoping is an antique.

Description reads............
Pale bottle green, with one large and some much smaller bubbles - one white seed and a number of very small black ones.
Glass is quite thick and pontil has been snapped, with dirt and discolouration around the sharp edges as to be expected from period snapped pontils. The hat has spent some of its life sitting inverted (used as a bowl/jar or whatever??), but the underside of the brim shows quite massive wear as per the pic - on the front and rear ends, with virtually none on the sides. Height is c. 3.5" and 5" back to front.
This is nothing like the posh hat frigger showing in Hajdamach, and my only book specifically on C18 and C19 coloured glass is a volume from 'The Collector's World in Colour' by Davis & Middlemas - which unfortunately doesn't show any hat friggers. However, the colour of this hat seems an exact match with what was a common colour of Victorian 'door stops/dumps' showing in the book - so I'm inclined towards thinking this hat is from a Midlands factory c. 1870.
The snapped pontil can be a confusing feature - I thought for some time that it was found only on first half C18 glass, but now know that it is occurs not uncommonly on some second half C19 pieces - especially, for example, on what are known as the 'thumb print' ale glasses, which are known to have been made around 1860 - 1880.
If the Mods wish to shove this on a new thread, no problem - it just seemed relevant to make a comparison perhaps with the other hat here. Must admit I did think that Mike's hat looked rather like a 'stetson' - and I wonder if the maker would have put the rim on one side only?
Of course, if I'm off the wall and mine was made in China last year, then I've wasted £3, but please be gentle.

Ref. 'Coloured Glass' - Derek C. Davis & Keith Middlemas - 1968.