Hello all,

Wondering if anyone can help pin down the possible date range for a clear 
British glass canning jar found in a context with TPQ 1915.

The base is stamped in a circular mark which reads as follows: 

the number "7" above the word "British"
and then below it "Made 6670"

I can provide an image of the jar if it would be helpful.

Any leads most welcome.  I am in London if anyone knows of reference 
resources to consult here.

Cheers and thanks,
Karen Wehner