personally I wouldn't date a jelly glass - they always expect to come home with me
........I know what you mean tho, they can be addictive - I seem to be knee deep in Victorian jellies and custards. Attached are pix of slightly earlier and less common sorts........... first shows lunar slicing on the foot rims, one of which also has an OXO band, so assume late C18 early C19.
The three together show ......... a mid C18 panel moulded piece, domed foot, snapped pontil c. 1750 - a six sided jelly c. 1775 (apparently there are eight sided examples, but presumably very rare). The last of these three is a rather plain jelly with pontil scar, folded top rim (folded over towards the inside) - but I'm unsure of date, what do people think? - acres of horizontal striations, stones, thickish foot, bit wonky, snapped pontil, slightly domed foot and lead glass - cud it be as early as 1750-60?
The last pic with what appears to be a taller than usual pan-topped jelly, is possibly mid C19, or perhaps a bit earlier - quite large at 6.25 inches (160 m/m). Cutting is quite prolific..... the knop, very bottom of the bowl and top rim are notched - a ring of oval punties under the foot - lead glass body adorned with well cut stars and swags. Diameter of foot rim is several mm larger than the top rim. Pity about the clouding in the lower part of the body.
Cud this be a 'captain's glass'?
Apologies for highjacking your thread Stuart - but thought you might like to see these. Don't know if you have a copy of the Delomosne catalogue showing the Tim Udall collection of C18 dessert glasses - well worth getting if not - and those would take you into overdraft territory!!