Thanks for the link Neilh. There are definitely similarities between the designs on your plate and mine. Like yours also, my plate is quite thick (about quarter of an inch/5mm). Does the edge of your plate have a kind of indented line running all the way around? (Mine does, which makes it look as if two plates have been pressed together to make one, but I don't know if that's possible/probable or just daft.) No initials in the stippling or anywhere else that I can see, and I've had a good look.
I've done internet searches for lacy glass, molineaux lacy glass, webb lacy glass, baccarat lacy glass - not much comes up. I haven't looked at Molineaux Webb though as I hadn't realised they were one and the same. Pictures of Hartley & Richards 'amber stain' pieces popped up at one point, which was interesting as not many pieces seem to have had added colour.
Thanks for the info. My quest has just begun and I've so many other things I should be doing . . .