Thanks for all your input, i have had a good look through the sites with no joy . I think 20th Century glass carry a picture of the decanter
but no manufacturers name.
There were so many small Swedish glass manufacturers in the past , maybe one of them?
The decanter is 175mm tall and 230mm with the stopper.
Nice polished pontil mark with the stopper number engraved.
It seems to have been blown into a two part mould with the seam running down the middle of the sides.
Tim