hi David....... just shows you the value of Patricia's book, which an essential volume for anyone with even the slightest interest in glass.
There are very similar shapes to yours, in S. & F., which shows masses of decorative patterns/cuts on sherries that were current from the 1870 - 1880 period as Christine has suggested - machine acid etching was another common embellishment. Apparently the shape originates commonly - with this thin plain stem - c. 1850 -60, with coloured versions mostly in green and red - the better quality examples having a collar, but I'm sure a lot have been reproduced in recent times - they don't seem to have the quality or shears/depression mark.
As a general shape for sherry, this type of bowl has had a very long life, and is still produced. In view of your comments about the foot finish i.e. absence of shears mark or pontil depression, my opinion would be that yours is a C20 product.
Does seem this bowl shape did exist 1760 - 1800 (George III period) but uncommon I think, and mostly the earlier stems differed a lot by having knops/multiple knops, balusters and other forms of cut/moulded decoration - a lot different to yours.
But look at how much you know of mid C20 table ware glass - about which I know just about nothing.
quote from Christine............ "so I can't afford to remember much" - don't believe it Chris(
) - you've a very good memory - it's only when you get to being 49 like me that you forget things.
P.S. presumably this should be moved to Glass ??