Where and When was this watch case made?

by Natasha
(UK)

I have a watch case handed down to me from my great grandmother. The hall mark on the back is a lowercase "k" in a gothic style font. It is sealed in a circle.

There is a empty embossed circle in the middle. On the other side of that there is an anchor in a square. Below the empty circle there is a "9" in a diamond and in a rectangle leading downwards from that there is ".375".

The only other marks on the case are a logo in a rectangle with a peak at the top with the initials "GS" and further below that just the numbers "106928". I would love to know the history of this peice so all advice will be greatfully received!! Thank-you