This is a quote from the 2002 J. Barefoot Catalog of G.B. Revenues;
""MEDICINE DUTY
Some were issued as standard stamps and others bore the name of a
proprietary brand. They were affixed to jars, packets, etc.,
and were torn when opening. Condition is, therefore, usually poor.
They were supplied without glue and then gummed to the medicine container.
Examples in pristine mint condition may be proofs, or unused stock
from periods of rate change. Used examples were generally uncancelled,
as it was considered that they would be destroyed in use. Defects
are therefore to be tolerated. Different formats were used according
to the size of the product assessed.""
Many different designs are listed/shown in the catalog and value starts
at 15.00 and goes up to 100.00. (values are in British pounds)
Here is a scan from the catalog with stamps similar to yours;
Issue years range from 1783(!) to 1923.
Perforated copies were available on request from 1905 onwards.
All are quite scarce and seldom offered for sale.
Prices are for AVERAGE copies, as they were seldom fine.
Here is another important note to consider;
"
Contemporary imitations were made of certain values to suggest that
exported bottles of medicine were "the real McCoy" (even if they
sometimes contained adulterated or fake medicine).
They were litho printed from 2 plates and may be recognised by
the overlapping of red and black, which would be impossible
for genuine stamps printed by the Congreve process."
After i showed the scan of this stamp i do not have a clue where i put it. Good thing i do not have an organized mind or i would be a multi millionaire.
It is probably still in the scanner, not sure what lice have to do with it going missing. Never mind it's a new year, anything could happen, and no doubt will.