The reason for your pontil scar is because of the need to attach the piece to a pontil rod after pressing - essential in order that the mould lines on the bowl can be fire polished (removed). When this had been done, the glass was removed from the pontil rod, and this was effected by snapping the join, thus leaving a rough/sharp scar on the underside of the foot. Maybe it was only the really cheap pieces that were left with a rough scar - the better pieces had this removed thus creating the ground/polished depression we see.
Don't know what books you have - both Hajdamach's 'British Glass 1800 - 1914' and Lattimore's 'English 19th Century Press-Moulded Glass' have sections on processes of press-moulded glass and well worth reading.
Hope you won't object to my adding a couple of pix.........
The first shows glasses with moulded decoration........mould lines can be seen on the feet and the outline of the lenses is not sharp. These would probably have been pub/tavern pieces, and show all three forms of pontil finishing. Date wise, I'd always thought of these being from somwhere in the period 1860 - 1920, but think now that the upper date is wrong - for example, they appear to be absent from the Sowerby (British) catalogues some time in the 1880's - maybe they started and finished earlier than I'd thought.
Second pic shows the difference when the decoration is cut .......sharp outlines of the lenses, better clarity of the metal, and absence of mould seams. Not quite sure of the intended social use of these - they are certainly much better quality, and one or two have an almost Georgian 'oily grey' colour, but I don't think these cut 'punties' were a form of Georgian decoration. However, perhaps they started a little earlier than the moulded lenses. The tall example at the back right I'm sure is Continental in origin, but as a form of decoration these lenses in a variety of shapes were very popular in the second half of the C19 - probably in many countries, and aside from drinking glasses they're found on jellies, custards and tea mixing bowls.
Would be grateful if anyone is able provide more accurate dating on these lensed drinking glasses.

Third and fourth pix show small moulded drinking glasses, and interesting in that the Rd. No. (578531 on both) appears in relief on the underside of the foot - slightly below the level of what looks like a pseudo foot rim. This No. was registered to Jules Lang in 1911, although not possible to say when these particular pieces might have been pressed. I thought the difference in bowl shape was intriguing (for the same Rd. No. anyway) - and shows what looks like a hobnail pattern with three mould lines which match up exactly with the sharp edges on the stems - a touch of neatness on an otherwise very utilitarian and cheap small pressed liqueur glass. I don't previously recall seeing any glasses where these seams lined up with edges on stems.
Apologies Pete if I've gone off topic a bit, so if the Mods wish to make a separate post of this waffle I'll understand - but hope some of it might be of interest to the couple of readers who've got this far
