Thanks for your suggestions. I am happy enough with the rummer/roehmer connection, although usually thought of these as German, with the coiled stem/pedestal style often applied to dark green wine glasses. But Dutch or Austrian brackets nicely.
The jug is quite massive at approx 18cms tall x 15cms diameter at widest part of body. The tumbler is almost 11cm tall.
There is considerable age-related micro scratch patination to the base and I would certainly be pleased to subscribe to a 1925 - 35 dateline.
Certainly glows nicely under the UV light.
It appears we may be unlikely to pin down the country, date, or maker any closer. Unless anyone else would like to chip in, please just share this serendpitous car boot find with me :thup: