Digby Antiques (Wiltshire) has dated this piece to the 1910s.
There is a date of 1916 engraved on the front together with an applied Christmas Tree.
London hallmarked date letter for 1911 makers mark Samuel Jacob.

There is also a retailers mark scratched into the silver J H Werner.
J H Werner were based in Friedrichstrasse. They made silver items, but obviously retailed items from other makers. They were one of the court jewellers.
L 27 cm
10.5 cm Diameter of glass.
Digby Antiques (Wiltshire) has dated this piece to the 1910s.
You can view the stock and full dealer information on the Digby Antiques (Wiltshire) Profile Page