Aramis Antiques has dated this piece to the 1910s.
The back of the brass frame also bears the engraved initial M and at the base the engraved words “Painted by Eleanor M Ross M.S.M.” Dated to c1910.

Eleanor M Ross is represented in the National Portrait Gallery, London by her portrait of the First World War nurse, Edith Cavell.
The miniature comes with a free standing folding rouge leather case.
Image dimensions : 8cmH. 6.5cmW.
Case dimensions when closed : 12cmH. 10cmW. 2cmD.
Aramis Antiques has dated this piece to the 1910s.
You can view the stock and full dealer information on the Aramis Antiques Profile Page