Nice. There is one very nearly identical to this, no.578, in Bickerton’s Eighteenth Century English Drinking Glasses. Same shape and size, also with notched rim and ribs, collar above rudimentary stem. The foot in the book has a stepped square-moulded lemon squeezer base. So in the book the foot is square like yours but with another smaller square layer on top instead of the first round layer on yours. He calls it a Monteith (which I thought was the same thing as a Bonnet) and c1800.