Something like 4.1/4" - 98mm, so probably too small for a wine, and I'm thinking more of a gin or dram glass (drawn stem variety). Nothing particularly special, but having just looked my other folded foot rim glasses, these are all showing snapped or sheared pontil marks, as opposed to this one which additionally has a nicely ground/polished depression. Typical of C18 folded feet glasses, this foot rim is wider (at 2.7/16") than the top rim (2.5/16") - and the foot is moderately domed, so probably not an especially early example. Produces a good ring when flicked, and has plenty of striations in the bowl and foot with a couple of minute seeds.
What do I make of the combination of fold and ground/polished pontil.........does the fold mean a definite date of around 1760/70 ish (as you'd expect), or might it be one of those uncommon folded/ground pontil examples from around the end of the Regency period - 1830 ish? All thoughts received gratefully, and thanks for looking.