Anthony — until quite recently there were always major trade buyers who did not want their glass marked. This applied even to prestigious designer signature ranges, with roughly half of Keith Murray's and roughly 10%–20% of Clyne Farquharson's unsigned (my guesstimates). If you didn't conform, you didn't get the order — so you conformed.
A significant proportion of Webb's
Gay Glass was unmarked, probably mostly for this reason. Other reasons include poor administration at stock control / order processing, and the acid on the stamp going dry as the girl worked her way down the row of inverted glasses.
Greg — I would have thought a little later, circa 1930s or possibly postwar. It's quite a Deco shape.
Bernard C.
