nope - not an inkling of an idea Anne

These things must have been in very common table use back in the first half/mid C20 - I see them almost everywhere I go - and in a profusion of colours and cuts, and I've had uranium ones too but no idea as to origin.
Outside of up market eateries etc., and of course posh GMB members, I don't think they see anywhere the same frequent use as fifty years ago - perhaps cheap ceramic bowls sounded their death knell.............. social habits have changes and they've probably died along with lidded jam pots, celery jugs, proper butter dishes etc.
I did have a dozen or so but now all gone except my Walsh Pompeian blue bubbled example.
It's tempting to suggest that if British then the date would be prior to mid 1940s - or whenever the U.K. ceased to put U. into glass - and if Continental then maybe later - is U. still used in some countries in table glass? You don't mention wear, or lack of ??
You have fifty + you say - do you think there's an issue there somewhere, or are you intent on feeding the five thousand on grapefruit instead of fishes and loaves.