Wildrose, welcome to the GMB.
This topic has been moved from the "British" forum to get a wider audience. Unless we know that something is almost definitely of a country for which there is a separate GMB forum, then the general Glass forum is the place to start.
Also, please note that in glass terms (and probably other things as well), "British" is still regarded as different from "European".
But is there any reason why this item could not be American? The very flared nature of the rim, and the rim edging are seen in some earlier American work.