I don't know that this would have been specifically for a pub or tavern - the capacity would be small for beer - although I suppose lemonade is a possibility. Are you saying soda simply because it doesn't have a lead glass ring?? Soda glass often shows a yellowish tint. Does the u.v. torch bring up any manganese greenish grey colour?
I've looked through Silber & Fleming, and the book doesn't contain a single example (that I can see) showing this exaggerated flared rim shape, so I might suggest this has its origin outside the U.K., or just possibly it's a regional piece - Scotland maybe - I believe they did some waisted shaped tumblers. Earlier tumblers have features that help to date them a little more accurately - but later pieces are generally so prolific that they are often defy pinning down.
I don't see this being a whiskey glass, but could be wrong.
This effect of the entire base showing the depression where the pontil scar was ground/polished was a fairly commonplace feature around 1870 - 1890 and perhaps later - and appears on drinking glasses from almost anywhere in Europe, so doesn't in itself help with origin, and as you probably know, cut flutes have been around for almost ever. Georgian fluts tend to have squared off tops, whereas later Victorian examples have rounded arch-shaped ones.
But since I'm a fan of tumblers then I have to say it's a good addition to the collection. Perhaps others are able to be more specific about this glass.

P.S. After 300 odd posts I don't consider that members are entitled to be treated gently.
