Hi everyone,
Thanks fo all your help over the Decanters, i seem to have found the answer from the Glass Museum, please see response below.
Thank you for the images of your decanter and yes I agree that the acid badge on your decanter was used from1926 till 1950 I know it seems like it is not very precise dating method but bear in mind the war years 1939 to1945 when there was no fancy goods produced ie decanters,cocktail shakers etc as it was all wartime production ie utility ware ,radar tubes etc you can narrow down the date of your decanters.I have gone through the catalogues from the late 20,s till mid 30,s and I am sure your decanter is pattern number 4022 which I think was produced right up till 1939 but not later, so I think it would have been made during the late 20,s to the late 30,s. the catalogues I looked at dated from those dates and pattern 4022 was produced all during that period.If you send me your address I send you a photocopy of the catalogue pages.