Hi guys, I'm back with some more info. (Sorry for the slow turnaround, visits to my grandmother are few and far between)
I have removed the bottom and the musical piece that it contained. The musical movement is made in Switzerland and the decanter also has 'Swiss' handwritten inside (see photos). There is text on the musical piece, you might not be able to see very well what it says from the photos but it says.... SWITZERLAND LADOR SteCROIX.
I also had a better inspection of the decanter itself. The head is not flush fitted, unlike what I declared at first. It is quite off centre and is at least 10mm from where it could be.
I am not sure if this is some sort of 'frankenstein' decanter which has been modified and painted by a third party or if this is a genuine original. I would be delighted if anyone can shed some more light on what this is.
Many thanks guys
This last photo shows how off centre the cork actually is in the head