It accords with illusrations in Silber & Fleming catalogues where other very similar single trumpet centre-pieces are shown, and are described Crystal glass flower stands. These catalogues were printed originally some time in the 1880's, and my opinion is that your piece dates somewhere from 1860 - 1880 (or a tad later).
quote ................."For floating flower heads or fruit or sweetmeats".................I'm fairly certain not for anything other than flowers. In a similar way to C20 float bowls, these bowls would have been for smaller flower arrangements.
This looks very dissimilar to Georgian/Regency glass (particularly a Georgian sweetmeat epergne), and bearing in mind the similarity to much of the Silber & Fleming material (much of which was imported from Europe), your piece may well not be of U.K. origin - thus accounting for features giving rise to problems with dating.