Hi ,
Can you tell if this decoration is wheel cut or stippled , its looks like it may be stippled to me , if so then the lighter area's will be dotted with the diamond point and the dark areas left untouched to create the contrast,
I would not be surprised if the glass was contemporary with the decoration,although in the 18thc style I am pretty certain it is a reproduction,if not contemporary then almost certainly sometime in the 20th century.
It may be an idea to contact the Guild of glass engravers and ask about the name,with no 91 on this glass the artist is no beginner.
cheers ,
Peter.