The British hallmark (to the right of "BM") is a Chester import mark for 1902. BM is the mark of the importer, B Muller & Son of Wardour Street, London. BM are the initials of the company's principal, Berthold Muller. Muller & Son were well-known, indeed prolific, importers of German silver around the turn of the century. The other marks are those of the manufacturer, Neresheimer & Son of Hanau, Germany. There is a section of this site on Hanau manufacturers at
http://www.925-1000.com/Fgerman_hanau_marks_01.html
Phil