whatever its origins it's a good genuine C19 tumbler and worth having in any collection. None of the States collectors have yet offered their advice on the mark - hopefully they will. The States were a little ahead of the Europe in the pressing game, and they may have had slightly different methods etc.
This is a good example to add to the Board's 'Glass Gallery Marks for future reference, so hope you can arrange at some time.

When similar decoration is cut (as opposed to pressed), you should be able to see some feint remains of the grinding wheel on the glass - most of the time no matter how careful the polishing, some slight evidence of those lines caused by the grit remain visible under strong light.
These lines will be at ninety degrees to the long axis of the tumbler.
U.K. published books on C19 drinking glasses (including tumblers) are almost non-existent, but John A. Brooks small booklet, despite running to only 32 pages, is well worth having. Title is 'Glass Tumblers - 1700 - 1900, and would imagine it's reasonably inexpensive.